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Re: My first self made EVAP
The investment isn't worth it and on warmish days they'll pretty much defrost themselves. Best bet is to avoid air to waters as much as possible in the first place and fit ground loops where possible. Simplifies everything and better returns.
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Re: My first self made EVAP
Hi BF
I have all new rads with individual stats
R's chillerman
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Re: My first self made EVAP
Quote:
Originally Posted by
al
That was what i thought BF, i wonder could you harness solar to defrost the unit, but on overcast days you're still left with an iced evaporator and bugger all heat.
al
Quote:
Originally Posted by
Bigfreeze
The investment isn't worth it and on warmish days they'll pretty much defrost themselves. Best bet is to avoid air to waters as much as possible in the first place and fit ground loops where possible. Simplifies everything and better returns.
Gents
I have no water meter and was wondering my mains supply stays between 10*c & 16*c all year round
would this suit a wshp, although I presume the water board would not appreciate my usage (if they knew)
R's chillerman
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Re: My first self made EVAP
You'd probably need about 2000L per hr for a water source unit CM, so you'll never run it from the mains.
I'd also second Al's advice and say put your money into insulation first. A poorly insulated house with rads is a no no for a heat pump no matter what some manufacturers and salesmen will tell you. You can look at a HP down the line, but bring your insulation level as high as possible first.
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Re: My first self made EVAP
Hi BF
thanx mate, I will get the insulation sorted, loft first, probably this/next weekend and look into getting the walls done asap, not happy with this gas system though as a couple of years back, gas was about £80 a month in winter, this summer its been £40 a month for hot water (3 x baths a day)....Got the boiler serviced and it shot up £80 a month......twat that serviced it, upped the system pressure and when heating, it lifted the prv and never closed as the filler loop was not capped off and was letting by, first I new about it was when I found green algae on back of house on day off....she said ''thats been like that for months, I wondered what the water was'' :(
Have it all sorted now but still £40 a month without heating, Gas is just toooo expensive
R's chillerman
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Re: My first self made EVAP
Quote:
Originally Posted by
chillerman2006
Hi BF
thanx mate, I will get the insulation sorted, loft first, probably this/next weekend and look into getting the walls done asap, not happy with this gas system though as a couple of years back, gas was about £80 a month in winter, this summer its been £40 a month for hot water (3 x baths a day)....Got the boiler serviced and it shot up £80 a month......twat that serviced it, upped the system pressure and when heating, it lifted the prv and never closed as the filler loop was not capped off and was letting by, first I new about it was when I found green algae on back of house on day off....she said ''thats been like that for months, I wondered what the water was'' :(
Have it all sorted now but still £40 a month without heating, Gas is just toooo expensive
R's chillerman
Not sure of gas or oil prices in the UK but here in Ireland you need a COP of 2.2 to match oil and with the upcoming increases in electricity you'll need a COP of 2.5-2.6. You won't match that in cold weather with an air source heat pump and rads, so investing in one is wasted money, especially where insulation is poor.
Insulate the nuts out of it, see whats the lowest temp you can manage to keep the rads at and keep the house warm and then you can decide whether a HP is suited. Any possibility of drilling a borehole?
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Re: My first self made EVAP
Quote:
Originally Posted by
Bigfreeze
Not sure of gas or oil prices in the UK but here in Ireland you need a COP of 2.2 to match oil and with the upcoming increases in electricity you'll need a COP of 2.5-2.6. You won't match that in cold weather with an air source heat pump and rads, so investing in one is wasted money, especially where insulation is poor.
Insulate the nuts out of it, see whats the lowest temp you can manage to keep the rads at and keep the house warm and then you can decide whether a HP is suited. Any possibility of drilling a borehole?
Hi BF
I dont know pricing here or how it works out either, all I know is the system I got was supposed to be more efficient (condensing boiler) yet my bills have doubled in two years, with gas price increases, so am at a loss to know if and how much benefit I have out of this system, the new rads I presume were a good choice as others were at least 15 years old and rooms heat quicker now, although having three floors is a pain as each floor is hotter than one below
Should be able to drill a borehole here mate, as there is rear access and as far as aware no obstuctions, the sewage runs through each rear garden but only about 1.5 metres from house. A figure of 16*c comes to mind (cant recall why) with gshp. What sort of depth/temp would I need for gshp and am wondering now also, why Mike has not taken this route with such low ambients
Mike
was this not an option for yourself or was it you just wished to overcome the issues of ashp
R's chillerman
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Re: My first self made EVAP
I think Mikes issues lied with the cost of drilling in Canada, local regulations and drillers just being difficult to work with in general.
If you give me the insulation spec and dimensions for the house I'll do a heat calc for you and work out a borehole depth and HP size
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Re: My first self made EVAP
Quote:
Originally Posted by
chillerman2006
Hi BF
thanx mate, I will get the insulation sorted, loft first, probably this/next weekend and look into getting the walls done asap, not happy with this gas system though as a couple of years back, gas was about £80 a month in winter, this summer its been £40 a month for hot water (3 x baths a day)....Got the boiler serviced and it shot up £80 a month......twat that serviced it, upped the system pressure and when heating, it lifted the prv and never closed as the filler loop was not capped off and was letting by, first I new about it was when I found green algae on back of house on day off....she said ''thats been like that for months, I wondered what the water was'' :(
Have it all sorted now but still £40 a month without heating, Gas is just toooo expensive
R's chillerman
CM, get rid of your vented system(it is really old school), just cap it then put in an expansion tank on the return side of the boiler and you will have a more stable system and no risk of corrosion in those steel rads of yours.
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Re: My first self made EVAP
Quote:
Originally Posted by
Bigfreeze
I think Mikes issues lied with the cost of drilling in Canada, local regulations and drillers just being difficult to work with in general.
If you give me the insulation spec and dimensions for the house I'll do a heat calc for you and work out a borehole depth and HP size
Hi BF
that will be great thanx, will get the insulation all done first, mate
R's chillerman
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Re: My first self made EVAP
Quote:
Originally Posted by
Bigfreeze
I think Mikes issues lied with the cost of drilling in Canada, local regulations and drillers just being difficult to work with in general.
If you give me the insulation spec and dimensions for the house I'll do a heat calc for you and work out a borehole depth and HP size
Yea, BF is right, all of the above but also, where I work the houses can have quite a small area for drilling and our code is that we must design for -20C even tho we rarely see it. The average house here would need 4-5 boreholes 200-250ft deep to meet the loads and the holes MUST be at least 10ft apart to keep from freezing the ground.
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Re: My first self made EVAP
Quote:
Originally Posted by
MikeHolm
Yea, BF is right, all of the above but also, where I work the houses can have quite a small area for drilling and our code is that we must design for -20C even tho we rarely see it. The average house here would need 4-5 boreholes 200-250ft deep to meet the loads and the holes MUST be at least 10ft apart to keep from freezing the ground.
Hi Mike
wow! when BF first mentioned borehole to me, my first thought was I wonder if I can dig that myself :confused: and save some money.... I would not have needed any heating for the house, I would have finished my days out digging my life away, haha:D
R's chillerman
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Re: My first self made EVAP
Much easier where the heat loads are lower, like most of the UK. Some areas here have design temps of -35 to -40 so it is a bit of a chore to design the system but that is not the norm.
Seriously, for your system, right now you can adjust things to lower the bill. How big is the house and what is the boiler input?
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1 Attachment(s)
Re: My first self made EVAP
Quote:
Originally Posted by
MikeHolm
CM, get rid of your vented system(it is really old school), just cap it then put in an expansion tank on the return side of the boiler and you will have a more stable system and no risk of corrosion in those steel rads of yours.
Hi Mike
missed this post earlier, mate
I have an expansion tank in the tank cupboard along with the pump
am presuming now its an expansion tank
if it is, can I just cap off the overflow/prv outlet ?
R's chillerman
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Re: My first self made EVAP
Now you have me a bit confused. I think that what I am looking at is a DHW cylinder, pump and an expansion tank. In some places there is a check valve (non return valve I think you call it) on the cold water coming in and to take up expansion when the tank heats up the exp tank must be there. But this may have nothing to do with space heating (not enough info).
Where is the boiler? Is there a heat exchanger in the tank?
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1 Attachment(s)
Re: My first self made EVAP
Hi Mike
house is three storeys, tank in picture above is on 1st floor, boiler is on ground floor, dimensions are 6x8 metres (per floor) could not find any info on bolier apart from model, as on attached pic...this was a right bogit & scarper install by one of her relatives, who dare not come round since and face me, wrecked the house, holes left in ceiling, ran skill saw along next to joists, then screwed 2x2 timber to joists and relayed floor, carpet deteriated along the gaps left behind, [deep breath] but still better than what was here which was gravity fed system with tank on first floor, very little flow to 2nd floor!
I think there is heat exchanger in tank, as bolier is not a combi boiler
R's chillerman
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Re: My first self made EVAP
OK, that boiler is a Baxi product with a max output of 15kw. IF your house is enclosed on two sides and the windows and air infiltration are reasonable, it should have no trouble keeping up with the demand. I see from the pic that there is a 3 way valve that divides between the heating the tank and the rads. I assume that the valve is normally set to heating.
Was the tank there before or or it new? Often tanks like that have a small HX and the boiler must stay on quite a while and at high temp to keep it heated. It is also possible that the setup syphons heat from the tank to the rads and the tank must call for heat more often. That part is just conjecture in regards to your system.
Why did the service guy turn up the gas pressure or was it just the water pressure?
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Re: My first self made EVAP
Hi Mike
the water tank was installed with boiler and yes it heats house no problem, in the winter I leave heating on 24/7 and just control temp via rad stats, one rad in hallway groundfloor has no rad stat, main wall stat normally set to, 21-25*c....yes inclosed 2 sides and new double glazing windows and doors, both heating and hot water work/heat up quickly
I called for service due to high gas bills this year and he adjusted the water pressure but left filler loop connected afterwards and this was now letting by, increasing system to mains water pressure, and when boiler came on, lifted prv and she just watched hot water come out of overflow for months, before I spotted algae on rear wall of house
Even though it works ok, I want to rip it out and start again at some point and I dont want any tube connections under the floor as want to lay new floor boards through out and dont want them lifted for anything once laid, I also have water tank in the loft/attic that I want shot of, which currently gravity feeds cold water to hot water tank/bathroom and toilets...the kitchen and boiler are all thats on mains water
need to work out what would be best to install here and get it all fitted next summer
R;s chillerman
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Re: My first self made EVAP
what;s your boiler temperature set to ?
anything more than 55'C and the boiler stops being a condensing boiler and just acts as a normal boiler
(return water is too hot for the hot moisture to condense on) and efficiency plummets (lower than a normal boiler)
also, make sure that stat on your hot water tank is set lower than the boiler temperature !
when my parents had there new heating installed, the boiler was set to 60'c, but the hot water tank to 80'C... so the tank always called for more heat, but the boiler could never take it over 60'c....
the boiler ran 27/7 trying to heat the hot water tank up.... I knocked it down to 50'C and now the boiler hardly ever runs ! :-)
can you take some more photos of the tank and plumbing there ?
by the look of it (and some of it is guess work here because I can't see everything)
you have a system boiler - so it just heats the same water pumping it round and round...
the 3 way valve picks where the water coming out of the boiler goes... it'll either go through the hot water tank heat exchanger or through the radiators.... there'll normally be a pressure valve here too so if there's a flow restriction etc.. some of the water will bypass from just before the valve and back down the return to the boiler (some valves can even split the flow between the tank/radiators)
if you have mains pressure hot water (looks like you do) the cold water into the bottom of your tank will come straight from the water main, with a non return valve and your expansion tank connected just after it (to take the pressure as the water heats and expands)
but... it looks a bit like your expansion tank is fitted to the heating water... I've never seen a system like that before.... but I'm not a heating engineer so it could be normal... you only need a small expansion tank here... and most boilers have one internally...
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2 Attachment(s)
Re: My first self made EVAP
Hi Mike
what temp can I take tank down to ?
boiler is mains fed for (manual) top up only, tank is gravity fed from water tank in loft
could be half my problem is 3 storey town house,
when its comfortable on ground floor, 1st floor is hot and top floor baking!
thinking of ducting top floor to ground in attempt to balance it out
R's chillerman
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Re: My first self made EVAP
There is a lot here.
First,if the boiler is set to 50-52 and the tank is set to 50, it won't turn off. Either increase the boiler temp or decrease the tank temp at least 5 deg.
Second, what is the mains pressure? It needs to be 2.5- 3 bar for the DHW to work properly and the heating for a 3 story house needs to be minimum of 1.2bar. It is possible that the mains is low and the exp tank is there for that but i doubt it. One problem is that you appear to have both an bladder type exp tank (which is turned upside down and should not be) and a old style fill tank on the top floor.
As I said before, get rid of the top one and cap the line. How many rads do you have in the house? I suspect you need a bit bigger exp tank than the white one, probably 25L or so as there is none in the boiler. You will need a pressure reducing valve from the cold water to the heating loop (placed beside the exp tank and all this should be on the suction side of the pump).
Condensing boilers do need to run at lower temps then non condensing but unless your natural gas is different than ours (which I doubt), condensing will start at 60C return water temp and gets better as you go down in temp. Even if you run the boiler at 80C you still will not get worse than the non condensing boiler but you are wasting energy.
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Re: My first self made EVAP
EXP tank in pic is on the wrong side of the pump. Turn down the stats on the top floor (DUH, I'm sure you have done that already.) I assume the boiler is not weather compensated>
Off to work now so i will blab on more when i get home.
Cheers
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1 Attachment(s)
Re: My first self made EVAP
Quote:
Originally Posted by
MikeHolm
There is a lot here.
First,if the boiler is set to 50-52 and the tank is set to 50, it won't turn off. Either increase the boiler temp or decrease the tank temp at least 5 deg.
Second, what is the mains pressure? It needs to be 2.5- 3 bar for the DHW to work properly and the heating for a 3 story house needs to be minimum of 1.2bar. It is possible that the mains is low and the exp tank is there for that but i doubt it. One problem is that you appear to have both an bladder type exp tank (which is turned upside down and should not be) and a old style fill tank on the top floor.
As I said before, get rid of the top one and cap the line. How many rads do you have in the house? I suspect you need a bit bigger exp tank than the white one, probably 25L or so as there is none in the boiler. You will need a pressure reducing valve from the cold water to the heating loop (placed beside the exp tank and all this should be on the suction side of the pump).
Condensing boilers do need to run at lower temps then non condensing but unless your natural gas is different than ours (which I doubt), condensing will start at 60C return water temp and gets better as you go down in temp. Even if you run the boiler at 80C you still will not get worse than the non condensing boiler but you are wasting energy.
Hi Mike
turned boiler off and used some hot water, static pressure is 1.4bar
tank set to 50*c, turned on boiler
and cut out at flow 72*c and return 61*c with pressure @ 1.8bar
Temps taken with strap probes 10cm from boiler and pressure gauge is on return
mains water pressure here is over 5bar
am pretty sure tank fill comes from loft/attic cold water tank, which gravity feeds from roughly 6 metres above and feeds into rear/bottom of HW tank
there are 7 rads (6 x rad stats, hallway ground floor no rad stat, runs off wall stat on first floor)
top floor rad stats now set to 3 of 5 and blob silicone so can check they not been fiddling with them
and will get the DHW set up on mains with pressure reducing valve and do away with loft tank and move expansion tank to other side of pump, this summer as I can send them on holiday then whilst I get it all sorted
for now turning boiler down to 55*c and tank to 45*c, should see some improvement ?
you say exp tank is upside down, is this an issue ?
thanx mate :)
R's chillerman
Quote:
Originally Posted by
MikeHolm
EXP tank in pic is on the wrong side of the pump. Turn down the stats on the top floor (DUH, I'm sure you have done that already.) I assume the boiler is not weather compensated>
Off to work now so i will blab on more when i get home.
Cheers
ps: boiler temp adjustment is useful :rolleyes: nice of them to mark out temps
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Re: My first self made EVAP
You can't remove the header tank without replacing it with something else. Its against regs for mains water to be sent to toilets etc. There must be a break tank installed. Also you've have no water if mains goes.
Don't know why you have an expansion tank at all. I can see no purpose on an open system with a gravity feed tank supplying the pressure. Although it is possible that the boiler/rads circuit is pressurised.
The tank will have one coil which the boiler water runs through and heats the tank. I'd imagine the 3 way valve is to divert flow either to rads or tank depending on demand.
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Re: My first self made EVAP
Quote:
Originally Posted by
Bigfreeze
You can't remove the header tank without replacing it with something else. Its against regs for mains water to be sent to toilets etc. There must be a break tank installed. Also you've have no water if mains goes.
Don't know why you have an expansion tank at all. I can see no purpose on an open system with a gravity feed tank supplying the pressure.
The tank will have one coil which the boiler water runs through and heats the tank. I'd imagine the 3 way valve is to divert flow either to rads or tank depending on demand.
Evening BF
header tank will have to remain then, cheers
the expansion tank, would this be for the heating system
from what I can make of this, there are two seperated circuits
the hot water which is gravity fed and
the heating circuit which is sealed? and mains fed
without expansion tank, how is system pressure controlled ?
R's chillerman
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Re: My first self made EVAP
Hi CM,
The water is gravity fed to the bottom of the hot water tank which pushes the hot water out the top of the tank and off to your taps. The boiler circuit is closed loop, circulating from the boiler to the rads or through coil in tank depending on demand. Pressure of 1-1.5 bar is fine here as the water going up will be balanced by the water on way down. The pressurisation is mainly to keep air out of the system, for rad performance and corrosion issues. The exp tank, as Mike said, should be tee'd in on the inlet side of the pump. I don't think any of this would affect your gas bills though
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Re: My first self made EVAP
Hi BF
thanx for the step by step mate, seems the setup is not as bad as first thought then, apart from need to move the exp tank and bring my temps down a bit, cheers
R's chillerman
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Re: My first self made EVAP
No its fine, just messy looking. Had a look at the pics there. Can't make out if the arrow on the pump is pointing down or up. I assume its up, so then the exp tank would be better on otherside but not the end of the world either.
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Re: My first self made EVAP
Quote:
Originally Posted by
chillerman2006
Hi BF
thanx for the step by step mate, seems the setup is not as bad as first thought then, apart from need to move the exp tank and bring my temps down a bit, cheers
R's chillerman
Guys, we are talking about the same thing. I was pointing out that there is no need for an expansion tank and a gravity feed/expansion tank so get rid of one or the other.
The water feed i was talking about drops mains down to 1bar and is adjustable. Add an approved check valve and you won't lose your boiler water if the mains go down. Every boiler system in North america works this way. Use a proper sized exp tank and you can keep the water oxygen free for years so your rads will last a long time and there will be no need to bleed rads every year as some people need to do.
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Re: My first self made EVAP
Quote:
Originally Posted by
Bigfreeze
No its fine, just messy looking. Had a look at the pics there. Can't make out if the arrow on the pump is pointing down or up. I assume its up, so then the exp tank would be better on otherside but not the end of the world either.
The problem with exp tanks with the port up is that sometimes air gets lodged in there and if the bladder doesn't stay wet, it doesn't last as long. That is why i keep them the other way around.
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Re: My first self made EVAP
Thanx Gents
will get a larger exp tank and mount up the other way and other side of pump, as there was loads of air in the system, pipes hammering for weeks, drove me mad, I presume I will get two tell tale signs if the bladder goes prior to moving/changing it, one being a pressure drop and two the outer wall will get hot to the touch, currently cool, all the info appreciated cheers
R's chillerman
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Re: My first self made EVAP
Quote:
Originally Posted by
MikeHolm
Guys, we are talking about the same thing. I was pointing out that there is no need for an expansion tank and a gravity feed/expansion tank so get rid of one or the other.
The water feed i was talking about drops mains down to 1bar and is adjustable. Add an approved check valve and you won't lose your boiler water if the mains go down. Every boiler system in North america works this way. Use a proper sized exp tank and you can keep the water oxygen free for years so your rads will last a long time and there will be no need to bleed rads every year as some people need to do.
You need the header tank in this situation Mike as we have different regs in the UK and Ireland regarding mains water,than the US and Europe do
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1 Attachment(s)
Re: My first self made EVAP
BF, you have said that mains water is not allowed to go to toilets...what water goes to the toilets?
is the drawing below not allowed in the UK and Ireland?
Attachment 7936
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Re: My first self made EVAP
No, afaik you need a break tank. Basicly a tank 200-300L where the mains water is collected and then distributed to taps, showers, toilets etc by either gravity feed or pump. You only run mains to the kitchen sink (drinking water) and an outside tap.
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Re: My first self made EVAP
The above is the most common set up here. I wonder if it is only historical reasons for not allowing other methods because we are as paranoid about legionnaires and other issues as Europe and the UK are. Using your method, the volume of water per shower may be less but no one cared about that 50 years ago so I cannot see the benefit of the system.
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Re: My first self made EVAP
Hi MIke
Maybe it was just in case the mains water supply was lost, when I was kid I remember this was a quite common occurance...those without water tanks, knocking on neighbours for a kettle full for some rosey lea
Cant remember the last time this happened as so long ago, but if thats due to where I now live (modern supply network, old addresses in London was victorian, I think....I know the sewers still are) and newer installations are less prone to leaks or if it was a case of supply issues back then, no idea
R's chillerman
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Re: My first self made EVAP
Morning CM. Are you doing this on a mobile while pissing away your employers time? LOL Or is it lunch time and you are in the pub.:D
You are probably right about the historical stuff but I would think it would change by now. One benefit of the the lower pressure from the tank is less water consumption from showers. Toilets will fill slow tho. How do those toilets that work on 3 bar pressure to flush work in the UK?
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3 Attachment(s)
Re: My first self made EVAP
Hi Mike
back on track for you, as we swayed off subject slightly,
R's chillerman
Quote:
Originally Posted by
MikeHolm
It's my first EVAP, just a fan, TXV, sensors and coil. Everything else is indoors but i won't show that to you yet as the wiring sucks and I have to clean it up:D Take note BF.
Quote:
Originally Posted by
chillerman2006
Hi Mike
nice shiny black mate looks pretty and neat job
picture is decieving - is there an opening at the bottom for air intake
at first glanc it looked like it was sitting on the ground and balancing
on 6 inches of earth. haha my eyes, must be age catching me up
R's Chillerman
Quote:
Originally Posted by
MikeHolm
It is off the ground by about 24" for drainage and it's British racing green, being a 60's BRM and Lotus fan, I thought that appropriate. Quiet as a church mouse. I was wondering if anyone would say anything....except for mumbling "what a pile of shyte":D
Quote:
Originally Posted by
chillerman2006
now you say it, my eyes can see its brg
whats 'brm' ?
and now my turn for the questions, with a cooling system you select the evap for required work
then add compressor/condensor/txv to match
How do you design a heat pump ?
Do you start with the condensor and then match components ?
R's chillerman
Quote:
Originally Posted by
chilliwilly
Did you make the coil yourself or did you buy it?
Quote:
Originally Posted by
MikeHolm
BRM was British Racing Motors who made some great racers in the 50s and 60s and Lotus is....well....Lotus.
I had a comp from a 12kw (give or take) heat pump that someone smashed up badly. it is a ZP40 and the only other good thing in it was the TXV and a couple of pressure switches. That was my starting point and the house is not too large so it may be a reasonable fit.
I used the least scientific method available to determine the coil, I added up the tubing surface area of the busted up wrap around (standard north american type) and the aluminum fin surface area and the volume of the tubing and using all the discussions with all you guys and a s**tload of research, I drew up the coil and had it made by a local establishment. I'll look for a coil end photo to post but I basically wanted a horizontal coil which appears to be the best for defrosting. The coil is 30" by 60", 4 row, 2 evenly split runs.
It will still take me a long time to get used to things like coolpacks so I didn't rely on it for anything although I tried. I don't know enough yet to use it with any certainty.
I picked 40C as my target temp for the buffer (450L, UFH and no dhw). I used the SWEP design software for the condenser (which I think may be a little bit small, but we will see as the year goes on) and I have bought lots of Hx from them before so I like the product. I cheated in that I didn't have to size a TXV (assuming my evap is sized right) so we will have to see how it runs, so far so good.
Real seat of the pants flying.
Quote:
Originally Posted by
chillerman2006
Hi Mike
your method appears logical mate
you have evap/comp/txv already matched, replaced evap with equal volume evap
then matched condensor to system, an half educated thought would be on setup
you will need to balance the system by air flow across evap and suction superheat/mass flow
to get your desired condensor temp but taking into account compressor protection
nice one mate, design is way beyond me now but maybe one day :)
R's chillerman
Quote:
Originally Posted by
MikeHolm
Thanks CM, I know my liquid fluid flow quite well but I'm still a novice in the "art" of refrigeration so it is actually a big step for me (old hat for many here I suspect)
Quote:
Originally Posted by
Bigfreeze
Nicely done Mike. You'll have good defrost draining from that design and protection from snow. Also the height of the ground and lack of legs makes a back build of ice also impossible. Good work mate.
If only I could progress my own projects as quickly:o
Quote:
Originally Posted by
mad fridgie
Where is the fan, is this induced draft or forced draft.?
The does the air blow up out of the evap or down out of the evap?
Quote:
Originally Posted by
mikeref
Mike, this now explains why you are difficult to find. Goober, just keep that office chair polished ;) and think about the fun you are missing out on by not being on the tools :p..Mike.
Quote:
Originally Posted by
MikeHolm
Attachment 7900
It had just finished raining so it looks wet. it is an updraft VSD unit. I haven't gotten to insulating the piping when i took the pic but it's done now.
Quote:
Originally Posted by
MikeHolm
All this will put me in the poor house for sure but it is great fun. I love the challenge.
Quote:
Originally Posted by
mad fridgie
Lets look at this as a purist
We do we want for efficiency, the highest possible air entering temperature, and air that is easiest to move.
So ,looking at the picture we can see that we are in fact pulling the coldest possible air (from the ground and recirculated air) into the evap coil, and driving air against its natural tendency to fall. air will fall naturally out of the evap coil.
Quote:
Originally Posted by
MikeHolm
The air movement as you state will be working against nature so I suspect the electrical draw might be a little bit higher but given the current draw I doubt it will be much. I haven't seen any heat pumps here that would be a downdraft because they are almost the units are offshoots of AC units.
The ground temp at the house will be a few deg warmer than the ground 1m away from the house because it is not that well insulated. I had contemplated having the heat recovery exhaust exit the house under the unit or even within the box but it was technically difficult to do.
If your air on and air off temps are only a few deg different and given the heat loss of the building at ground level (there is a full basement), I'm not sure that it will be an issue. 25 years ago we regularly had temps of -25 in the depths of the winter but the last few winters I can count very nights below -15C with most at -5 to -10. I use -15 as a goal which is why I was interested in the digital scrolls performance.
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Originally Posted by
MikeHolm
Mad, what do you think the performance change would be if the the fan was removed from the picture?
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Originally Posted by
mad fridgie
What yo have built is an excellent cond, (and this is what everybody does, even in this application)
Here NZ the ground temp in the morning can be a good 6C below air temp,
So for example if the fan where underneath, drawing air downwards and discharging along the ground, it is possible that the SST could be 6C higher (in the above case), that could increase duty by close to 15%.
(off the top of my head)
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Originally Posted by
MikeHolm
Food for thought, as they say, I will have to look up norms but local temps (local meaning within a 1m or so) are very influenced by what is around them. Is the wasted heat through the wall of the house going to influence the air on temp when the coil is 600mm above the ground. I have never seen a study on this but I am sure it exists....somewhere
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Originally Posted by
Bigfreeze
I'd have to disagree with you there Mad. There would be almost no difference in the air temp a 300mm off the ground and that off air 1.3m off the ground. I would say almost none tbh. The disadvantage of downdraft in Mikes design is that it could encourage short cycling of air, which would be much worse than any potential gain.
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Originally Posted by
MikeHolm
Even tho it is 600mm off the ground and has free air on 3 sides? Maybe i am not getting the meaning of short cycling correct...
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Originally Posted by
mad fridgie
The comment is not particular to this evap, The air is drawn past the ground to enter the evap, hence must be colder, the air exiting is colder and more dense than the ambient so will fall to low level, encouraging short cycling.
Many other factors do need to be considered exiting air velocity, free area in which it is to be mounted.
Not to say that you would just mount the fan underneath.
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Originally Posted by
MikeHolm
Here is the next Evap I had in mind,
Attachment 7921
In the winter The solar panels are often unable to reach the temp needed to help the DHW tank but does contain enough heat to add to the evap. The question is, at what sustained temp would the coil be considered to be overheated? 40C? Assume 410A. Probably not enough info;) typical eh...
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Re: My first self made EVAP
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Originally Posted by
MikeHolm
Morning CM. Are you doing this on a mobile while pissing away your employers time? LOL Or is it lunch time and you are in the pub.:D
You are probably right about the historical stuff but I would think it would change by now. One benefit of the the lower pressure from the tank is less water consumption from showers. Toilets will fill slow tho. How do those toilets that work on 3 bar pressure to flush work in the UK?
Hi Mike
Mobile Internet (HSDPA) 2mb connection, pukka, can work and play at the same time
R's chillerman
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Re: My first self made EVAP
Pulling a vacuum eh? bored?
Still looking for thoughts on a combined coil? I don't know if there are any other combi coils there (boiler or other options)