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Thread: My first self made EVAP
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11-10-2011, 11:17 PM #51
Re: My first self made EVAP
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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11-10-2011, 11:46 PM #52
Re: My first self made EVAP
If the World did not Suck, We would all fall off !
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12-10-2011, 12:04 AM #53
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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12-10-2011, 12:04 AM #54
Re: My first self made EVAP
If the World did not Suck, We would all fall off !
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12-10-2011, 12:12 AM #55
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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12-10-2011, 12:36 AM #56
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 chillermanIf the World did not Suck, We would all fall off !
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12-10-2011, 01:02 AM #57
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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12-10-2011, 01:25 AM #58
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 chillermanIf the World did not Suck, We would all fall off !
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12-10-2011, 01:51 AM #59
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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12-10-2011, 11:42 AM #60
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 chillermanLast edited by chillerman2006; 12-10-2011 at 04:09 PM.
If the World did not Suck, We would all fall off !
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12-10-2011, 01:56 PM #61
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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12-10-2011, 01:59 PM #62
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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12-10-2011, 03:44 PM #63
Re: My first self made EVAP
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
ps: boiler temp adjustment is useful nice of them to mark out tempsLast edited by chillerman2006; 12-10-2011 at 03:59 PM. Reason: added pic
If the World did not Suck, We would all fall off !
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12-10-2011, 07:39 PM #64
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.Last edited by Bigfreeze; 12-10-2011 at 07:41 PM.
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12-10-2011, 07:52 PM #65
Re: My first self made EVAP
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 chillermanIf the World did not Suck, We would all fall off !
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12-10-2011, 08:23 PM #66
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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12-10-2011, 08:44 PM #67
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 chillermanIf the World did not Suck, We would all fall off !
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12-10-2011, 08:56 PM #68
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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12-10-2011, 09:14 PM #69
Re: My first self made EVAP
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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12-10-2011, 09:18 PM #70
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12-10-2011, 09:29 PM #71
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 chillermanIf the World did not Suck, We would all fall off !
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12-10-2011, 11:01 PM #72
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12-10-2011, 11:25 PM #73
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?
boiler and tank drawing.jpg
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12-10-2011, 11:39 PM #74
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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13-10-2011, 12:06 AM #75
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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13-10-2011, 11:15 AM #76
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 chillermanIf the World did not Suck, We would all fall off !
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13-10-2011, 11:25 AM #77
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.
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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13-10-2011, 11:27 AM #78
Re: My first self made EVAP
Hi Mike
back on track for you, as we swayed off subject slightly,
R's chillerman
If the World did not Suck, We would all fall off !
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13-10-2011, 11:30 AM #79
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13-10-2011, 11:32 AM #80
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)Last edited by MikeHolm; 13-10-2011 at 11:34 AM.
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13-10-2011, 11:34 AM #81
Re: My first self made EVAP
Hi Mike
when in defrost, I presume the fan is off ?
would it be worth insulating the box the evap sits in ?
also you are going for an angled evap this time, whats the benefit here ?
R's chillerman
(maintenance - get 8 hours for what takes me max 4)If the World did not Suck, We would all fall off !
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13-10-2011, 11:39 AM #82
Re: My first self made EVAP
Yes, the fan is off for defrost, I may use hot solar heated water when available to defrost but we will see. The angled coil will aid in getting rid of liquid during defrost and it means I can mount the unit between the houses when there is only 1.8m of space, without pissing off the neighbour.
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13-10-2011, 12:07 PM #83
Re: My first self made EVAP
Hi Mike
many ventures all in one here, mate, certainly keep you busy and hopefully fat wallet when finalised
another gremlin you have which warmer climates dont suffer is a drop in specific heat transfer
if looking at -20*c .... glycol mix needs to be to -30*c ..... which I think is roughly 50/50
cp of water is 4.18 where glycol is 2.36 ....... lowering efficiency of the already lower temps, heat transfer
was thinking too that maybe during winter you often get clear skys and low sun as we do here, making your solar systems more available for work, but 'think' I recall you saying panels require +15*c to work well and winter sun is not as strong
certainly got your work cut out here mate, finding the right balance of heat/energy/heat
R's chillerman
Argh ! A thought - what about magnification of the sun onto solar ?If the World did not Suck, We would all fall off !
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13-10-2011, 12:17 PM #84
Re: My first self made EVAP
Nope, the normal hot water panels I use produce good heat in -15C -20C as long as it is sunny, which it often is in the winter but i may only get 30C from the panels and not 70-80C that i would like.
Water/Glycol is 60/40 typical. There are additives that help the freeze/boil characteristics somewhat but you are right, transfer is not great. We are used to it in this business as there is not a lot of option except for system that drainback the water to an inside storage tank when not in use.
All in all, solar does work well but financially, not unless you have some subsidy as you have.
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13-10-2011, 12:25 PM #85
Re: My first self made EVAP
Hi Mike
thats good, got my +/- round wrong way
you can start fires with a magnifying glass, is this something that can be used to increase heat
or is this something that is already part of a solar panel (built in)
seems strange how some western countries subsidise some products and not others
R's chillermanIf the World did not Suck, We would all fall off !
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22-10-2011, 10:01 PM #86
Re: My first self made EVAP
I had a lot of t-stat and pump wiring to do before I started up the HP. Yesterday started it up for the first time with a floor heating load, got very high pressures for the first couple of minutes (tank was cold too???) then it settled down but pressure is getting near 400psi at 40C water temp and TXV is hunting a bit. I think I will put in a receiver tank if it will help the hunting issue. I really want something to keep the the pressure from passing the 400psi mark but I'm not sure what the best method should be...any ideas?
superheat is running between 15-16F with a cold tank and 6F when it is near setpoint. DT on the water side in and out of the tank is about 4-5FLast edited by MikeHolm; 22-10-2011 at 10:04 PM.
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22-10-2011, 11:09 PM #87
Re: My first self made EVAP
Hi Mike
if valve hunting, first confirm you have liquid feed by taking discharge pressure and convert to saturated temp, then check you have a lower temp on liquid line, if sure you have liquid feed then its just a case of getting the valve set up right
you can increase discharge temp by increasing suction superheat, this will then give you a higher discharge temp at a lower pressure but on the flip side higher suction superheat will reduce mass and compressor work is increased to move the same mass ...
what refrigerant are you using ? R410a for instance has high pressures but lower temp to pressure than other common refrigerants
400psi is 27.2 bar which if R410a is fine
R's chillermanIf the World did not Suck, We would all fall off !
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23-10-2011, 03:36 PM #88
Re: My first self made EVAP
Thanks CM, I will look at it again during the week.
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23-10-2011, 06:42 PM #89
Re: My first self made EVAP
Ignore the fact you have low discharge temps from cold. Its always the case when starting a heat pump. Only when the floors return water temp is 20C plus can you really zero in on whats happening in the fridge circuit.
Starting the machine in cold weather you should actually help your discharge temps by slowing the pump speed until return is about 20C.
What gas are you running. 407C i assume? 400psi is pretty high in that case. What are your inlet outlet temps across HX on water side?
I would install a receiver. Just to give yourself a bit of leeway when it comes to refrigerant charge.
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23-10-2011, 07:03 PM #90
Re: My first self made EVAP
HI BF, it is a 410 machine but I will have to go back and take measurements tomorrow. Problem is that I am only running on stage one as i haven't put a 2nd stage switch on it yet and I am wondering what the best way would be to do that. Like I said above, I'm getting 10.5A @230VAC on stage one and this seems a bit high to me.
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24-10-2011, 08:55 AM #91
Re: My first self made EVAP
If its 410a then you're not a million miles out at 400psi. Your condensing temp should be about the same as your outlet temp give or take a degree or two. 400psi would be about 47C condensing.
Dual stage? As in two compressors? I assume they're two 7kw units. If so, again you're not a million miles away assuming that that figure includes the fan motor and the fact you're running up towards 50C.
Are you running a seperate coil for each compressor?
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24-10-2011, 12:06 PM #92
Re: My first self made EVAP
It is a ZPS two stage copeland,
ZPS40K4e summary.pdf
ZPS40K4E performance.pdf
On full output it should pull 9.4A at 10C evaporating and 40 condensing and I will check what pressures we are running today, but last i checked, I was drawing more power than that and i hadn't reached a 40C tank temp yet.
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24-10-2011, 04:39 PM #93
Re: My first self made EVAP
Are you sure its evaporating at 10C. That would be high for this time of year. 0C would be more likely. According to the weather service its 11C in Toronto today, so no way its evaporating a 10C. 3C maybe.
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25-10-2011, 12:20 AM #94
Re: My first self made EVAP
I stand corrected, I meant that ambient was 10C. I haven't been down to the job today as they are finishing the wood stairs and I can't get in the basement. I will see tomorrow.
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23-11-2011, 11:20 PM #95
Re: My first self made EVAP
OK, the R410A HP seemed to be running well enough while the weather was a bit warmer. What bugged me most was the high current draw 15.5A when the data sheet says it should be 10.5A.
I put on the gauges and I get suction 4.72Bar, -10C,
discharge is 28 Bar, 48.3C
Liquid from the buffer is 49C and out is 53C
air on 9C and off is about 5C (comp stopped as it was going down and I was about to take pipe measurements on the evap) and the sun went down anyway.
I was going over in the morning and when I got there the EVAP was a solid block of ice.
I think it is overcharged but I have a feeling there is something else as well (perhaps condenser is too small). Any thoughts?
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23-11-2011, 11:34 PM #96
Re: My first self made EVAP
I'd definitely expect that kind of ampage draw on that size compressor with that much differential between low and high side. Try to keep the outlet temp down to 45C if possible. Running at high temps in heating mode will write off your compressor in a short space of time.
Could well be overcharged as your condensing temp and water outlet temp should be within 1C of one another and right now they're 4-5C apart. Your subcooling should be close to your return temp too.
Whats controling defrost and what type of defrost is it?
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24-11-2011, 12:13 AM #97
Re: My first self made EVAP
That's the problem, it is a York board with defrost built in. The manual gives no indication except that there are jumpers across pins depending on the size of unit. I assume that is for defrost time. There is a bonnet sensor, defrost sensor as well an ambient sensor.
I assume it just triggers the reversing valve.
It also mentions something called "Hot heat pump" but does not define what that means.
Bugger....
The above temp is the highest the unit gets to as my tank setpoint is 49C
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24-11-2011, 12:32 AM #98
Re: My first self made EVAP
I would say cond side is very good, suction does seem very low for that ambient and condensing pressure.
(when dealing with temps and pressure which are very close, you may just find it is the accuracy of the instruments that you are using.)
The amps are spot on, for those conditions.
You need to work out why your suction is so low, at 9C and high SCT you should be well above freezing.
Do you have sight glass in the liquid line?
what is suction return temperature at the comp inlet.
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24-11-2011, 12:38 AM #99
Re: My first self made EVAP
Suction return about 6" from the inlet was -10C.
I am thinking of putting in a bigger pump to get a bit more out of the condenser. What do you think?
As BF says try to narrow the gap some....I thought the condenser was a bit smallLast edited by MikeHolm; 24-11-2011 at 12:43 AM.
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24-11-2011, 12:44 AM #100
Re: My first self made EVAP
Unfortunately there is no sight glass, my next concoction will have one