Heat Pumps

Gurgle · 16-02-2006 11:46am

megadodge wrote:

The lack of ground is exactly my problem though. I just don't have the space and a borehole seems quite expensive.

AFAIK, they're no good in Ireland. You'll end up with whats basically an electric central heating system which is going to be expensive to run.

megadodge wrote:

I also noticed when looking at his Pump that the water temperature was around 75 degrees Celsius which is considerably higher than what's mentioned for Geo.

Doesn't sound right.
Do you have the make/model of the pump?

megadodge wrote:

would aerothermal seem a good choice ?

When the air temperature is over 9°C but still cold enough to need the heat on, aerothermal appears to be a good option.
Do some calculations

http://www.iol.ie/~wicklowweather/Monthly%20Reports/Annual2004graphs.htm

Ayla · 23-02-2006 2:44pm

This is my first post to this site, and I think there's a lot of really good info on here (there's no better sales pitch than experience).

My husband and I recently attended the Self Build Exhibition in Belfast and while there got to speak with a number of heat pump companies...what a variety of information we got! It's hard to drudge through the sales jargon and try to decide what is, in fact, the best product out there. I have to say, though, there was a good bit of well-intended but mis-informed sales reps who couldn't say why their companies were better than the others ("because we just are" is one answer we received...needless to say, we didn't talk long with that company).

I don't know if this is against posting regulations, but I can say that out of all the companies we spoke with, my husband and I were most impressed with the information we received from Sweco. The reps genuinely knew our area (Donegal) and have had a good bit (40 years) of experience building and maintaining heat pumps. All Sweco does is heat pumps (they don't do underfloor systems, etc) and so all of their eggs are in the one metaphorical heat pump basket. Seems to me that they'd know what they're talking about.

When talking with them, some of the information they gave us did, in fact, conflict with the information from the other companies. However, keeping in mind their experience and knowledge which they supported with facts, my husband and I came to trust their side more than the others.

All that said, here's what they said (and I'd like to hear from you all as to what you think)...

If we were living in Scandanavia, where the temps drop considerably below freezing for months on end, geothermal would most definitely be the most effective method of heating the home. However, here in Ireland the worst of the winter temps rarely drop below freezing for more than a few days (in fact, they said the average Donegal temp in January is 6.9), and therefore we can extract heat from the air.

In fact, according to Sweco, air is much more efficient than ground because of the poor conductivity of the ground. Let me explain...

The temp of the ground 1-3 metres down takes months to change, so it may retain some of the summer heat until Nov-Dec, but will remain cold until May-June. The geothermal pipes will extract heat from about .5metres away, and because of the same poor conductivity, the temp of the earth in that .5metres will become steadily colder as the winter progresses. It is true that the Irish ground rarely freezes solid, however if the earth around the pipes is becoming colder, and in fact the pipes themselves are eventually covered in a layer of ice, that means the heat pump has to work harder to extract the same amount of heat. This is also why geothermal systems require anti-freeze pumping through the pipes.

On the other hand, the air temp may get cold (even below freezing at night), but the converse side is that it heats up very quickly every day. Keep in mind the average daily temp even in Jan-Feb is around 8-10. You can install your air pumps on a southern exposure to use the sun's heat as well. The aerothermal pump only works when it has to (when the inside air temp drops), and even the unavoidable icing of the unit can be dealt with much more efficiently. This means the pump doesn't have to work as hard to extract as much heat.

And as far as initial costs, geothermal is really expensive to install b/c of the piping, whereas aerothermal just has a couple of units to bolt onto the side of the house.

I know this is a long post, but I thought the info we rec'vd from Sweco was very interesting and I'm really interested in hearing what you all think. My husband and I are doing our own direct-labor self-build this year for our own 2,000 sq. foot home, and we're trying to do the most energy-effecient and logical build possible. Let me know your thoughts.

Ayla · 23-02-2006 4:33pm

Sorry, me again. Forgot to mention that Sweco said the water in their pump does reach 75C because of the direct exchange system (I started tuning out here b/c it got a bit too technical...just tell me it works).

However, an important thing that I did remember was that the temp must reach 75 b/c the water has to be sterilized. The other heat pumps get the temps up to 50-60, but then require an immersion to reach 75 for sterilization.

Any thoughts?

Gurgle · 24-02-2006 10:42am

Ayla wrote:

The other heat pumps get the temps up to 50-60, but then require an immersion to reach 75 for sterilization.

Any thoughts?

Why would you want sterile water in your central heating?

slayer91 · 24-02-2006 11:50am

Lads,

Have installed a Sweco Aerothermal System in my house since Dec2005.
No doubt about but the people involved are very helpful.
My unit is 14KW (2x7kw Heat pumps). House size is 2300 sq ft. Underfloor down stairs and rads upstairs.
Things to remember:

1: Size the Heatpump unit correctly. Check and double that the rating of the heatpump is suitable to cover the heating for your house. Sweco are very helpful in this regard, but by all means double check with appropiate third party.

2. A 14kw heatpump does not means I am using 14kw of electricity, it is the amount of heat the system can transfer to teh 500l tank. The actual electrical usage is determined by the size of the motors in the heatpumps units. MIne are 1.4kw each. So when the heatpump is running I am using 3kw of electicity. So for every hour they run, it is costing me 51cents( 3 x .136c where 13.6 cents is the cost of a ESB unit of electricity).

3. However, if you run the system at night and have the ESB night saver rate then you automatically cut the running cost in half.

4. At the moment, I run the rads for 2 hours in the evenings and charge the underfloor during the night.

5. The previous poster point is also correct, Sweco are only concern at keeping the water in the tank at a certain temperature, if your underfloor or rads or house insulation is not up to stratch, then it will keep drawing water and this will cut in the heatpump and your costs will increase.

Have more information but posting is getting a bit long at this stage.:( Will add more later.

Regards

smadger · 24-02-2006 2:18pm

slayer91 wrote:

Lads,
4. At the moment, I run the rads for 2 hours in the evenings and charge the underfloor during the night.

Interesting - when you say charge during the night, how long do you do this each night and how long does that keep the floor warm for?

If, say, you had the heating on from 3 am to 7 am, would it then stay warm up to and during the evening? Or would it need to come on again in the evening?

Cheers,

Smadger

Ayla · 24-02-2006 2:23pm

Gurgle wrote:

Why would you want sterile water in your central heating?

Good question...my only guess for needing sterilization in your pump is not for the central heating but for the water that'll be used for cleaning, etc. No point washing your dishes w/ water that's germy, right?

Any other ideas?

billy_beckham · 26-02-2006 5:19pm

Hello Slayer,
I too have an aerothermal heat pump from Sweco which was installed in our newly built house just before Christmas. We are moved into the house about a month now and i am not really happy with system. For a number of reasons,

1. Amount of esb being used. Our system is the Sweco 11 so it gives 11kw of heat but uses 2kw to run the heat pump. there are also 3 x 3kw backup immersions. I have two of these off at the moment but the system still is using about 80-90kw/day. Now even allowing for night rate esb(which we have) thats still about E10 a day.

2. Like you we have ufh downstairs and rads upstairs. I have the ufh running most of the time except for an hour in the morning and evening when i run the rads.I do not run both together as the tank temp drops hugely. But i am not happy with the temp that is being achieved on either floor.

I have some questions on the system you have and how you run it and we appretiate any help you could give me!

1. What temp do you supply water to your ufh at?
2. You say earlier that you only run ufh at night. Is that enough to keep house warm during day?
3. Are you happy with the radiator part of your central heating ie temp wise?
4. Sweco sized my heat pump and reccommended the 11kw model with the balance made up by the boosters. Yet you have 14kw for a slightly smaller house??? The figure they used for heat loss was 45w/M2. So 2700ft2 = 250m2. 250 x 45=11.25kw, 2300ft2 = 210m2 x 45 =9.45kw So how come they reccommended a larger pump for your house? What heat loss figure did they use?
5. In general are yo happy with your system? I spoke to Sweco and they told me that the system will be hard on electricity fo a couple of months until the house is fully dried out. I that your experience?

Look forward to your reply!

slayer91 · 27-02-2006 11:01am

Hello

1. What temp do you supply water to your ufh at?

The temp setpoint for the underfloor is set by the underfloor system and not Sweco. My SWECO setpoint is set at 44 deg, with an hystersis of 2. For me, this means the underfloor runs at an average temp of 35deg

2. You say earlier that you only run ufh at night. Is that enough to keep house warm during day?

During mild weather (outside temps above 8degs), this would be enough, however, I would think that the underfloor would need to be boosted by 1-3 hours during the day if temps were lower.

3. Are you happy with the radiator part of your central heating ie temp wise?

I would prefer if the rads were hotter, but in fairness Sweco pointed this out from the start. Normal oil biolers heats the rads up to 50-60 deg, Sweco can only heat up to 35-45 deg. To overcome this, I got my plumber to oversize the rads in the bedrooms. Also since the rads are in bedroom so do they need to be on all the time????

4. Sweco sized my heat pump and reccommended the 11kw model with the balance made up by the boosters. Yet you have 14kw for a slightly smaller house??? The figure they used for heat loss was 45w/M2. So 2700ft2 = 250m2. 250 x 45=11.25kw, 2300ft2 = 210m2 x 45 =9.45kw So how come they reccommended a larger pump for your house? What heat loss figure did they use?

This is the 64k question that everyone must get right when choosing this type of system. I, too was offered the 11kw unit and used extra insulation in the underfloor and everywhere else in the house. However, just before the system was installed, I have another talk with SWECO and they recommened the change to the 14kw. To be honest, I am glad I followed their advise even though it kind of blew the budget a small bit. The extra heating power is well needed during this cold weather.
Using the backup heaters is a no no. Alright for very, very cold nights, but I have mine set so that they will not come on. (cold rather than poor!!!!)

5. In general are yo happy with your system? I spoke to Sweco and they told me that the system will be hard on electricity fo a couple of months until the house is fully dried out. I that your experience?

In general, yes, I am happy with the system. The system controller could be more intelligent. Yes, it is hard on electricity but careful use of the night time rate can reduce the cost.
Also remember these months will be the most expensive! once the milder weather starts, the system run time are dramatically reduced. Like any other system, you would need to run it for a least a year to see if it is working out or not.
My only fear for you is that the system is undersized for for your heating requirements.

Question for you now, is your domestice hot water very hot, as in, too hot. Did you fit a manually mixing device to this part??

Regards

megadodge · 27-02-2006 1:53pm

Slayer, thanks for your input.
Bottom line though - how much are your ESB bills this time of the year ?

When it comes down to it, the cost will have a big bearing on whether I go for it or not.

billy_beckham · 01-03-2006 10:15pm

Hi Slayer,
many thanks for your reply!
In relation to the hot water, we got our plumber to fit a thermostatic mixing valve on the hot water from the 500l tank. It mixes the cold supply to the tank with the hot leaving it to give water at about 55-60oC. Would reccommend doing this for two reasons, the water from the tank IS too hot and could scald. Also you would not be drawing heat from the thermal store unneccasarily.

I guess i am going to just have to play around with my set-up to achieve reasonable running costs!

Regards.

VINNIEB · 01-03-2006 10:41pm

Not sure if this is allowed but here goes,

Give these guys a call, HEATLINK IRL, Tullamore, 0506 24062. I am building a house soon, and enquired about Geo-thermal and underfloor heating, they were very helpful explained everything.

Boggle · 02-03-2006 5:46pm

HI Vinnie - out of interest, how big a house are you building and what will your estimated running cost be per year?

josephd · 03-03-2006 2:13am

Hi Ragazza,
Your brothers are right in so far as oil is handy. You won't go wrong with handy in the short term.
Your parents are understandably dubious with fairly recent heating systems.

However, if you expect to make an impartial judgement, it will take some time.

My quick answer is that you should strongly consider putting in a "wood pellet burner", as opposed to an oil burner, or gas burner. Oil as we know it, is gone practically or is/will become, too expensive.
Wood pellets (sawdust, shavings, and chippings, bound together), is a replenishable source, in so far as a new tree can be grown rapidly, to replace any that is burned.
Your parents may see some sense in this, but not the speed of growth, with regard to trees currently grown, perhaps. Maybe they do.
It is also said to be "carbon neutral" (a tree requires co2 gas to grow, and will release it when it is burned. However the new tree will remove it.

This really means that enviromental taxes/levies, are unlikely to raise the price, but the reverse, possibly (though I doubt we will see prices ever going down).

The heat pump.
The consistent claim from manufacturers, or their sales people for the last ten years, is that if you put in one kilowatt of energy(in this case, electricity), then you will get somewhere close to four kw's back.
Some will say that it is a little lower, which is not bad for that length of time (time for truth).

If it is anywhere close to that figure, then it is good and efficient.

However, the efficiencies of a heat pump, oil burner, pellet burner, gas burner or anything; is no use to you.......unless there is a holistic approach, if you will. Sorry, I forgot electrical efficiency (bar heaters, storage heaters, fan heaters, etc.) as well.

Your electricity bill will likely go up, and a bad house will waste every bit of it. Except a good fridge and microwave oven. lol.

Back to the heat pump.
The coils (loops) can go either horizontally or vertically, in your lawn for example. However, there are systems in place in this country(though more common in France) which employ neither a horizontal or vertical looping system. They work overground , and claim to recover energy from the air itself and in conjunction with coolants/refrigerants/liquids with low boiling points. As indeed other heating systems employ, such volatile liquids.

The investment is large, mainly due to the piping network and isolation valves (which stop or allow water to pass, triggered by thermo stats, and "zone settings"). Modern labor costs, of course don't help.

That said, the heat pump is a good investment, but not on its own.
Also, there isin't really a house which requires no heat/energy (around here). If you answer the door, a stiff breeze may well dampen ideals. Lol.

What can also be deceptive is energy bills which don't factor in the "bags of coal" etc., on top of electricity, oil or gas.

But I can only imagine your confusion, having being there to some degree. Who does one believe?

My only suggestion is that you consider an energy specialist, before you plan your house. Look for experience within an Irish climate or the climate of whichever country you live in, and experience in modern Ireland and European implications for the future.

If you need research, google the University websites of America which at least try to be objective, as they don't try to sell you something, as well as try to not sell you something , lol. But bear in mind, the climatic and fuel differences, which are expensive variables.

P.S. A friend of mine is currently stressed with the same issue. He went for the overground system, but had and has problems gathering information on it.
The salesman is setting the stage, it appears.

CJhaughey · 03-03-2006 1:39pm

josephd wrote:

Also, there isin't really a house which requires no heat/energy (around here). If you answer the door, a stiff breeze may well dampen ideals.

josephd I would have to disagree with you there, In fact in Galway there is a passive house out in Moycullen, made by Scanhome it is a big place 164sqM.
The door is actually doubled so that the stiff breeze won't trouble you so much.
I wonder if people actually think about energy costs when building their own houses? , I mean a person builds a 3000sq ft house and then complains that it is hard and expensive to heat? Get real people if you want to build big at least have the common sense to build in a sustainable manner where you don't need 3000 litres of oil to heat a house per year.

Ayla · 03-03-2006 2:04pm

CJ -

Forgive me for being dense, but exactly what part of Josephd's statements were you disagreeing with? I don't think anyone on this site is building a 3000 sq ft home, and if so, I think they're all being realistic about the heating costs, etc. involved. In fact, the point that they're all here, on this site, discussing possible ways to build as efficiently as possible, refutes any argument you were making. I'm not sure I understand the point you were trying to make to this audience...?

CJhaughey · 03-03-2006 2:44pm

Ayla wrote:

Forgive me for being dense, but exactly what part of Josephd's statements were you disagreeing with? .

The part that said:Also, there isin't really a house which requires no heat/energy (around here)
Ok I apologise for the rest of the rant but I will also quote

billy beckham wrote:

I too have an aerothermal heat pump from Sweco which was installed in our newly built house just before Christmas. We are moved into the house about a month now and i am not really happy with system. For a number of reasons,

1. Amount of esb being used.

His house is not 3000 sq ft but instead So 2700ft2 = 250m2.
sorry i was 300 sq ft out.

josephd · 03-03-2006 10:23pm

CJhaughey wrote:

josephd I would have to disagree with you there, In fact in Galway there is a passive house out in Moycullen, made by Scanhome it is a big place 164sqM.
The door is actually doubled so that the stiff breeze won't trouble you so much.
I wonder if people actually think about energy costs when building their own houses? , I mean a person builds a 3000sq ft house and then complains that it is hard and expensive to heat? Get real people if you want to build big at least have the common sense to build in a sustainable manner where you don't need 3000 litres of oil to heat a house per year.

Hi CJ (that name is familiar?),
Sorry, what do you mean by "the door is actually doubled". Is it two doors or what?

Great dicussion, thanks.

CJhaughey · 03-03-2006 11:33pm

Josephd

Yes there are two doors, one outer and another inner door.
I find it interesting too.
If you are in Galway you should try and see it sometime it is a very interesting idea, a big house that needs no or very little input to stay comfortably warm.

VINNIEB · 04-03-2006 12:12am

House is about 2000 sq ft, Est running cost estimated at E18 per week, based on previous feedback from customers, still waiting on quote.

josephd · 04-03-2006 12:19am

Hi CJ
Unless it is very much different than the conventional two door system, one at a short distance, inside the other, they're all inherently flawed.

Wow! what a remark, you might well say or not, but consider this;

With a swinging door (hinged, left or right), air is going to be displaced by the fanning action of the door. Warm air is either going to be pulled and/or pushed by the surface area of the door.
A sliding door is much better where it is the edge of the door (fifty to seventy millimetres, or whatever), which cuts into or through the air.

Such things are of marginal benefit, and no benefit all where individuals might insist on slow passage through doors.

Which reverts back to the heat pump theory or practice. If you put one watt of energy into anything, and get more than that back, you're doing well. If you put in one watt and get a conservative three watts back, then that is fantastic.
Any other wastetage is another matter, including door construction and usage.

I did explore the possibility of a revolving door which would be hung from above, opposed to someone having to enter sections or quadrants. The drawings and workable theory was a bit too futuristic/weird/deemed unnecessary/bereft of support, at the time.

Run with this yourself if you see any sense in it, or laugh at it.
It is better suited to industrial applications, over domestic, due to the size needed for comfort.

Consider a revolving door as an insulated glass cylinder, on end. No sections or segments, but just an empty space within it. (Its hung from above, not supported from the ground up).

Have an opening (one, and modern regulation width or well above).
Step in through the opening, and pull the door around through 180 degrees.

As well as eliminating any fanning action, you could step out in your intended direction, and swing the door again through 180 degrees.
The cold air (thought slightly warmer, and time dependent) within the "door" or revolving chamber would be returned "outside".

What do you say to that?

megadodge · 06-03-2006 10:35am

JosephD, thanks for your input as I'm very undecided at the moment what heating system to use. I'm interested in your comment -

My only suggestion is that you consider an energy specialist, before you plan your house. Look for experience within an Irish climate or the climate of whichever country you live in, and experience in modern Ireland and European implications for the future.

Could you suggest one, or where could I go looking ? Obviously an independent voice with nothing to gain.

Thanks.

CJhaughey · 06-03-2006 10:06pm

josephd
I like your lateral thinking and problem solving.
I just think that it is easier to get a little carried away with the minutiae of energy saving with doors.
The passive house apparently will have a micro heatpump docked to the solar panels and possibly a windturbine to provide a small amount of heat.
While your idea for a door has merit in practice it would be so expensive to fit and manufacture that you would most likely blow your heatpump budget on the entrance alone.
I would agree that it would be of most use in a commercial passive building, maybe patent search it?
I spoke with the owner of the passive house and he said the main reason for twin door is that to have a single door that was good enough to match the rest of the houses insulation it would be unfeasibly thick and also rather ugly, rather like a bank vault door.

josephd · 09-03-2006 10:06pm

Hi Megadodge,
Impartiality may be difficult to find.
Free advice/suggestions, will have issues and so will commercial interests. The world will revolve without perfection I'm afraid, lol. And only because of it, perhaps.

Anyway, the best specialist may be yourself and your ability to differentiate between semi-truths and what is left.
You may have noticed Ciaran's post on the earlier heat pump thread? Now he is a retired Mech. eng. and still had to use his own observations over the word of his contractor (re the depth of the installation).
He is also correct in that any company which may send a client/potential client, to other customers, would not and could not get accurate feedback.

The very bottom line as I see it (with a broad engineering background and analogue electronics) is that the majority of heat pumps are fantastic and any percieved problems come from incorrect installation, the over view of the house, rather than the heat pump itself.

If you put one kilowatt into anything and get "three to four", in return, then any problem is not with the heat pump, per se.
(if any electric motors can perform as they should, any other percieved faults lie elsewhere).

However, that is the generic heat pump itself (there isn't much to them, really).
The looping systems provides some variables.

Basically there is the horizontal. This is no more than a loop or coil of "pipe" sunk about a foot or whatever, into your "lawn".

The Vertical. There is sometimes a little confusion over this, depending where in the world you are talking about it. In some parts of America, this is similar to the horizonal system, only that it is in a "trench" of some depth.
Another perception is that the vertical (more local perception) is basically a loop that is put down a "hole", and as far as possible (though not quite to Australia, lol).
This is said to be better as the horizontal system will absorb local heat from above and below that loop. It must be remembered that you may only have ten inches (250 mms) to a foot (300mms), above it. Should such a loop absorb (as it is designed to do), local heat, then its general efficiciency will drop.
Does this make sense? It the loop/coil of pipe, has cooled the local area by a degree for example, then it would have less to play with (or what some describe as temperature differential).
A long vertical loop would have some advantage efficiciency-wise, in this respect.

Air or over ground system. The popular defense of this is that the average temperature of Ireland over a year is somewhere close to 8 degrees. The manufactures of these systems will argue that ground temperature (whether horizontal or vertical), does not fluctuate much. Would you agree with that?

Air temperature can relatively be many times higher, so should you have Zero degrees celcius over ground, then my friends manufacturer claims that its efficiency is still over three. (One kilowatt in, and three out)
So we must all do our own maths on this balance???

So statistics must be local to Ireland, from any manufacturer.

Some people will watch Duncan Stewart (excellent program), but fail to realize that while he is getting info. on a system which is in use in Hungary for example, that his objective is not to argue a systems merits (in relation to Ireland) with the engineers of that country. It should be treated as it is seen, and in the temperature context of that region.

Another implication as well as available surface area (in the case of the horizontal loop), is that some areas of Ireland are difficult to drill, or too expensive to drill. Some of the Granite regions of Connemara for example, or the marble of Kilkenny for another example.

There may even be further implications with regard to the bogs of Allen?

Anyway, I just heard today that a company which used to service wind/electricity generators internationally, has branched into drilling large diameter holes which might facilitate small towns supply.

Wouldn't such a solution save a lot of headaches and expense? Though, I'm not sure that the political will in a local regard, exists.

Conclusion; If we had a few more items as efficient as any workable heatpump, we'd be doing well.

Quick question to any one who cares to answer; Would it be cheaper to boil a cylinder of water with a large microwave oven over an electrical emmersion?
Another thread perhaps.

air · 10-03-2006 12:24am

josephd wrote:

Quick question to any one who cares to answer; Would it be cheaper to boil a cylinder of water with a large microwave oven over an electrical emmersion?
Another thread perhaps.

No quite the opposite in fact. An electrical element submerged in water performs a near 100% efficient electrical -> heat energy conversion.
A microwave oven will have iron, inductive and resistive losses in the initial transformer stage, inefficiency in the microwave emitter and leakage of radiation from the cooking area + it runs a light (if we're to get really pedantic

).
So no, stick to the immersion, keep the tank well insulated.

Evergreen · 10-03-2006 1:00pm

Hello,

This is a very interesting discussion.

If anybody is interested in doing a heat load calculation on their house then let me know, I have an Excel program that I use everyday for determining the size of heating requirements a house will need. It takes in all elements of the house, i.e. wall type, numbers and type of windows/doors, ceiling insulation, etc.

CJhaughey · 10-03-2006 1:06pm

I am interested can you PM it to me?

smadger · 10-03-2006 2:49pm

Hi Evergreen - I'll take a copy if it's going.

Evergreen · 10-03-2006 5:02pm

Hello,

I don't know how to transfer items within the forum, is it possible or do I need your email address to email directly?

smadger · 12-03-2006 1:13pm

Me neither, so I sent you a PM with my email address.

Cheers

Heat Pumps

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