My first self made EVAP

[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 Take note BF.

[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

[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"

[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

[chilliwilly]

Did you make the coil yourself or did you buy it?

[MikeHolm]

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

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.

[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

[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)

[Bigfreeze]

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 Take note BF.

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

[Goober]

What a pile of shyte!

Sorry...couldn't resist. It is very nice looking though.

[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?

[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 ..Mike.

[MikeHolm]

004small.jpg
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.

[MikeHolm]

All this will put me in the poor house for sure but it is great fun. I love the challenge.

[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.

[chillerman2006]

Hi Mike

did not want to load up your thread with info you already have

so have started a new one, some maybe of assistance

http://www.refrigeration-engineer.co...at-Pump-Theory

Also the attached doc is referring to uk temps that rarely hit minus 15*c (norm -5*c where I am)

& lists ashp's as not economical with low ambients !

R's chillerman

[MikeHolm]

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.

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.

[MikeHolm]

Hi Mike

did not want to load up your thread with info you already have

so have started a new one, some maybe of assistance

http://www.refrigeration-engineer.co...at-Pump-Theory

Also the attached doc is referring to uk temps that rarely hit minus 15*c (norm -5*c where I am)

& lists ashp's as not economical with low ambients !

R's chillerman

CM, the description as written probably needs some editing as it may be more true in the American context but from what I have seen, European heat pumps are designed quite differently. American units focus on air heating, starts with cooling (residential units) and heating usually an afterthought. I may be wrong but most of the resi HPs in Europe use a slab coil for the evap (comp indoors and designed for heating load) and most US ones use a wrap around coil with the comp in the middle.

[MikeHolm]

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.

Mad, what do you think the performance change would be if the the fan was removed from the picture?

[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)

[MikeHolm]

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)

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

[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.

[MikeHolm]

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.

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...

[chillerman2006]

Hi Mike

obviously these Gents understand these systems well

what I can see from their comments are

updraught could short cycle if air off is not ejected far enough away from the unit, as air off being cooler than ambient will natuarally fall once out of air flow - induced draught in this case would through the air further (I think)

downdraft could short cycle if unit is too close to the ground and in the morning when the ground is cooler than ambient and air off

but once the ground is at or above ambient then the air should naturally disperse along the ground

stuck in between two possiblities here, I would be inclined to go for down draft

I would then use a smoke stick, to be sure of air flow and if short cycling still then add a chimney to the air on

Once all finalised the unit and chimney if required can be covered and made to fit in with the surroundings

your other point mentioned of wrap around coil seems to also have advantage, as wasted heat from the compressor can be transfered to the evap, but not something you considered ?

R's chillerman

[MikeHolm]

CM, the wrap around coil is a space saver but does nothing for ability to defrost properly which, going through most of the problem posts here, is the root of the issue. Short and effective defrost is one key to a trouble free cost efficient system. There are benefits to a downdraft in terms of fan electrical cost but it think it is slim at this point.

[mad fridgie]

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.

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.

[MikeHolm]

Here is the next Evap I had in mind,
SolarEvap1.jpg

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...

[chillerman2006]

CM, the wrap around coil is a space saver but does nothing for ability to defrost properly which, going through most of the problem posts here, is the root of the issue. Short and effective defrost is one key to a trouble free cost efficient system. There are benefits to a downdraft in terms of fan electrical cost but it think it is slim at this point.

Hi Mike

I was not thinking of defrost issues when commenting on wrap arounds, as I am still playing catch up with you's on HP's

not knowing/seeing how wrap arounds are configured, I was thinking of compressor heat, how ever minimal transfered to the cooling coil, would be a welcome increase at low ambients

I know I am missing a big part here (again) with defrost issues (still to learn) but I would have thought mounting in the traditional upright way on the houses wall, would be beneficial, as you would then have the warmest air possible as air on, that being warmer than ambient due to heat loss of the property... My reasoning here is if I park my vehicle facing the house my windscreen rarely freezes with minus ambients but if facing away it always freezes

R's chillerman

[MikeHolm]

Hi Mike

I was not thinking of defrost issues when commenting on wrap arounds, as I am still playing catch up with you's on HP's

not knowing/seeing how wrap arounds are configured, I was thinking of compressor heat, how ever minimal transfered to the cooling coil, would be a welcome increase at low ambients

I know I am missing a big part here (again) with defrost issues (still to learn) but I would have thought mounting in the traditional upright way on the houses wall, would be beneficial, as you would then have the warmest air possible as air on, that being warmer than ambient due to heat loss of the property... My reasoning here is if I park my vehicle facing the house my windscreen rarely freezes with minus ambients but if facing away it always freezes

R's chillerman

Take a look at most of the people coming on with a poorly preforming HP. A big majority use Japanese (or their Chinese knock offs) HPs with placement or airflow issues due to defrost.

Google any york or lennox AC unit and you will see a picture. I would say they make up 95% of North American HPs.

[al]

mike

i love the build, you're going to find out so much from this!!

This is something i saw last year:

http://www.irishecoplumbing.com/ther...c-solar-panels

Have you seen these BigFreeze?

as i said before, best air source i've seen, standard cold room evaporator outside with a condensing unit made from off the shelf parts.

al

[chillerman2006]

This is something i saw last year:

http://www.irishecoplumbing.com/ther...c-solar-panels

Have you seen these BigFreeze?

as i said before, best air source i've seen, standard cold room evaporator outside with a condensing unit made from off the shelf parts.

al

Hi Al

it all looks very neat......but So Much of it ! (massive)

I am at early stages of deciding what to fit to my house

and this lot would turn a large double room into a single or loose half my garage !

Would I need all this for a 3 x double bed house ???

R's chillerman

[MikeHolm]

Al, do you know this guy? Irish EcoPlumbing? It looks like a neat enough job but the there is no way that the panel does much for the system.

It is basically the same performance as a plastic swimming pool panel, and you need 20m2 to get any heat from them. Also, because they are not enclosed in a greenhouse (glass, insulation, aluminum frame etc) like water heating panels are supposed to be (or vacuum tubes), they will only work during sunny periods when the ambient is above 15C. Otherwise they will re-emit as much energy to the environment as they absorb. I really hope no one buys it. It can be improved but it is an iffy technology as is.

I spoke a bit too soon....

Just had a look at the system and it is a 134A based panel that looks like it is about 1m2 or so. I suspect that while it would get more heat output than a regular system of the same size, would it be 8 times? doubtful. also, how would they deal with fridge lines that go up 3 storeys, for example). Knowing how many issues we have with regular solar systems, this one must have been fun to perfect.

[MikeHolm]

CM, you have seen my website. There are lots of pics of 2 panel systems that would provide 50-70% of the DHW for your house. If you want to tie it in with a heat pump, it will be more involved but whatever you do, if you want to use solar for space heating you should have a lot more panel area and 75-100L of storage for every m2 of panel area. There are some exceptions to this rule but it would involve a trip to the UK, and lots of beer.

[al]

MikeH

There's a guy by the name of quentin gargin (fairly unique name!), he's based in west cork and knows lots about renewables, i've spoken briefly with him and come to the conclusion that solar isn't economical at the minute.

i don't know who is behind the product i mentioned, just purely as a different way of looking at it, i have the same questions about ice buildup etc.

CM, if you can get all that gear at cost price then go for it but it wouldn't be for me! Reinsulate the house first, then worry about heating.

al

[al]

Some interesting debate here and some good info too:

http://www.boards.ie/vbulletin/forumdisplay.php?f=1041

not sure if you have to register to view or not.

al

[chillerman2006]

Hi Mike

argh, am with it now thanx

was looking at that lot for just an ashp set up and was shocked

now I see its solar heating too, will have a closer look through your site tomorrow, cheers

bed for me now and will speak with the brewery here asap

R's chillerman

[chillerman2006]

CM, if you can get all that gear at cost price then go for it but it wouldn't be for me! Reinsulate the house first, then worry about heating.

al

Hi Al

very good point mate, not long fitted (2year ago) new hot water/heating system

and loft and walls need insulating for sure, cheers

R's chillerman

[Bigfreeze]

mike

i love the build, you're going to find out so much from this!!

This is something i saw last year:

http://www.irishecoplumbing.com/ther...c-solar-panels

Have you seen these BigFreeze?

as i said before, best air source i've seen, standard cold room evaporator outside with a condensing unit made from off the shelf parts.

al

Have seen them alright Al. Same principle as the ice stick and same fundamental problem, once the outside temp goes to 7C or under you get ice formation on the panel which causes evap temp to drop, which creates more ice and so on so forth. I looked at something similar myself years ago but passed on them as they are only good for producing hot water in mild weather.

The reason a cold room evap works well is that its designed to work with moisture. Most AC type units aren't.

[Bigfreeze]

Hi Al

very good point mate, not long fitted (2year ago) new hot water/heating system

and loft and walls need insulating for sure, cheers

R's chillerman

Have you rads or ufh CM?

[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

[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.

[chillerman2006]

Hi BF

I have all new rads with individual stats

R's chillerman

[chillerman2006]

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

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

[Bigfreeze]

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.

[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

[Bigfreeze]

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?

[chillerman2006]

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

[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

[MikeHolm]

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.

[chillerman2006]

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