Heat Pumps - post here.

sheff the ref

Deleted User wrote: »

Would it be possible to integrate the heat pump into a normal well ?

Drilling a well specifically for the heat pump would be really expensive but would probably be better than laying pipes over a large area of the garden ?

You need a very deep borehole to provide the same collector area as a horizontal ground collector with sealed circulation pipework. A normal well would not have that depth.

However I believe you can use an open pipe system but that could cause its own problems. Dirty Water. Preventing Freezing etc.

fairwind

Hi
Looking at possible borehole collector geothermal
Any ideas on costing and running .
We're close to sea in west cork
Might this help us in perhaps shallower hole required if we hit close to seawater?
Also we plan on ufh in 290 Sqm house well insulated.
Don't want oil so it's this air water or possibly Lvp solar.
We would hope to future proof by eventually running pump from photovoltaic.
F

sheff the ref

For the liquid leaving the heatpump, you need X amount of surface area of closed loop pipe for the liquid to circulate sufficiently. That applies regardless of the ground conditions so you cannot take short cuts on the length of pipe needed for the collector.

The exception is if you are actually pumping through an open loop e.g sucking into the heatpump from one side and blowing out the other. Wouldnt fancy doing that with salt water.

fairwind

Thanks for the info, I was wondering would the proximity of the sea improve COP. I understand that an open loop is not a good idea with salt water.
Have you heard anything re the heliotherm system? Thanks
F

sheff the ref

Havent met anyone with a working Heliotherm system and if I was to invest in any system I would need to talk to a few people who had them working through the cold winter.

badgerhowlin

fairwind wrote: »

Hi
Looking at possible borehole collector geothermal
Any ideas on costing and running .
We're close to sea in west cork
Might this help us in perhaps shallower hole required if we hit close to seawater?
Also we plan on ufh in 290 Sqm house well insulated.
Don't want oil so it's this air water or possibly Lvp solar.
We would hope to future proof by eventually running pump from photovoltaic.
F

PM sent

cwboy

Hi. I am principal of a school who have been offered grant aid to install renewable energy. One of the options proposed was four air to water heat pumps to replace our oil boiler. A Borehole was mentioned but was almost ruled out on time and cost constraints. The school was insulated with fiberglass in flat ceilings and walls pumped three years ago.

We also plan on installing pv panels to take some of the burden on electricity.

What are peoples opinions on this option? The school has twelve classrooms and a multi purpose hall along with other space. The level of grant aid would not cover the works and the school would have to cover 20% of the cost.

Thanks

al2009

Depending on oil usage then yes, fairly straight forward retro fit, it may be possible to retain existing rads. What part of this green and pleasant land are you in?

Condenser

If you are running existing rads I would advise against it. The temp required would be too high in order to get a good return. Your COP would be very low especially on A2W. Its likely that a school would have poor insulation values also which would further reduce the chances of running at a decently low temp. In times such as these its hard enough for schools to have money for the important things. You're money would be best spent elsewhere in this case imo.

Alot of HP suppliers are trying to market heat pumps as straight swap solutions for oil boilers. They are the furthest thing from and need to be installed in the right manner in the right application. I met with two potential customers with similar proposals in domestic situations just today and advised both of them not to bother with a HP as the application did not suit.

cwboy

Thanks for the replies.

I am based in Carlow. The school is reasonably well insulated but doors would be open at breaktime leading to heat losses. With grant aided funding, would we be foolish to ignore a way to rid ourselves of oil? The oil bill is around seven thousand a year. The installer reckons we can elimate 80% of this with the heat pumps.

Are the photo voltaic panels good enough yet to really help with the electricity burden?

Condenser

cwboy wrote: »

Thanks for the replies.

I am based in Carlow. The school is reasonably well insulated but doors would be open at breaktime leading to heat losses. With grant aided funding, would we be foolish to ignore a way to rid ourselves of oil? The oil bill is around seven thousand a year. The installer reckons we can elimate 80% of this with the heat pumps.

Are the photo voltaic panels good enough yet to really help with the electricity burden?

Your installer is talking through his proverbial in that case. You won't reduce you bill by 80% with an A2W heatpump in even the most perfect of circumstances and certainly not in the application you have explained. I'd be surprised if you ever broke a COP of 3.5 on that system. You need a COP of 2.2 just to be the equivalent of oil.

PV doesn't stack up for a residential set up at the moment because there is no decent feed in tarriff available and therefore the payback just isn,t there. You'd just be paying for your next 15yrs electricity up front. However in your case if you're getting grant aided it is certainly an option worth exploring. It all depends on how much panel you will get for the grant provided as a deciding factor in whether you choose pv or not.

al2009

cwboy

It would be a good move, 80% might be optimistic. I can pm the number of a company that have carried out comparisons on oil vs hp for nursing homes and similar buildings.

alec

Condenser

al2009 wrote: »

cwboy

It would be a good move, 80% might be optimistic. I can pm the number of a company that have carried out comparisons on oil vs hp for nursing homes and similar buildings.

alec

Al i'm surprised that a man with your background would be endorsing installing a HP on a system where the condensing temp would be so high constantly and on a building especially an A2W systems with the potential for deep evaporating temps and a propensity for icing of the condensers, especially in our humid/moist conditions . Would these heat pumps be ran in series and if so what would the defrost strategy be as you could not have one defrosting while the others are heating.
What would you consider would be the lifetime of the compressor of a unit condensing at 50C for such extended periods of time?

cwboy

al2009 wrote: »

cwboy

It would be a good move, 80% might be optimistic. I can pm the number of a company that have carried out comparisons on oil vs hp for nursing homes and similar buildings.

alec

Thanks for the reply. Would love the number if you could pm it. Having spoken to one of the installers today he said the rads would be between 20 and 45 degrees depending on the outside temp and could be boosted by oil if needed. The rads would be on all day to maintain a constant temp.

Outkast_IRE

cwboy wrote: »

Thanks for the reply. Would love the number if you could pm it. Having spoken to one of the installers today he said the rads would be between 20 and 45 degrees depending on the outside temp and could be boosted by oil if needed. The rads would be on all day to maintain a constant temp.

Honestly the only way you could prove this system would work is to forget about installers advice etc, salesmens advice, and hire in a comapny to do a full energy audit, you would advise them that your looking to reduce heating costs of the building etc.

And let them do their audit and they should be able to tell you straight up what your alternatives are, no BS , no salesmen/installer advice.

Personally i am having a hard time seeing how you would save money with the air to water running 24/7 , especially with kids in the buildings where they will be constantly in and out of classrooms etc.

All your rads were sized day one to run at a certain temperature, if you drop this temperature there is a sizeable chance rooms will be cold , especially coridoors and larger areas such as halls etc.

Also the installer telling you 20 to 45 degrees , sure a 20 degree rad wouldnt heat a room very well at all !! and lets assume the oil boosts it then your back to square one using oil to supplement a brand new system, not to mention you will have the maintaince of both oil and air to water now!!

As i said, proper energy audit is the only way to go with the audit focused towards choosing possible new systems.

Condenser

cwboy wrote: »

Thanks for the reply. Would love the number if you could pm it. Having spoken to one of the installers today he said the rads would be between 20 and 45 degrees depending on the outside temp and could be boosted by oil if needed. The rads would be on all day to maintain a constant temp.

You wouldn't even get heat off ufh at 20C. If you put your hand in 20 degree water it would feel cold and it is. Body temp is 37 degrees so as a consequence if you stood in a room naked you would be giving off more heat than a rad of similar surface area at 20C.

Outkast_IRE

Condenser wrote: »

You wouldn't even get heat off ufh at 20C. If you put your hand in 20 degree water it would feel cold and it is. Body temp is 37 degrees so as a consequence if you stood in a room naked you would be giving off more heat than a rad of similar surface area at 20C.

Exactly what i was pointing to..........

The rads are sized to work at a set temp, at this set temp they will heat the building.

These installers now say , it will work 20 - 45 degrees and then you can boost with the oil !!!!!!!!!!
Honestly its along time since i heard such ****e.

This building would end up using a hell of a lot of oil , and would need the additonal expense of a buffer tank probably so two different heat sources can contribute to the same building.

hugo29

is there any way to determine what depth boreholes are. we have geothermal system but we dont seem to be getting a decent temp in from them

sheff the ref

Basically a borehole has to compensate for the surface area that would be achieved by a horizontal collector to meet the requirements of a heatpump of a given size. I was involved with a job where there were 4 if not 5 boreholes and from memory I think they were 200m deep each.

I have specs somewhere for borehole depths needed for heatpumps with different KW. I do know at the time that collectors were being undersized in a bit way by different companies, and perhaps that has happened with boreholes.

The temperature from the heatpump should be relatively constant regardless of whether the collector was undersized or not. Basically the difference an undersized heatpump would make is that the pump keeps circulating the waterantifreeze working harder to get the temperature gain, hence drawing electricity and doesnt get much of a chance to cut out. That wouldnt really affect the temperature heading to the internal heating though I would have thought which should be roughly 40 degrees

hugo29 wrote: »

is there any way to determine what depth boreholes are. we have geothermal system but we dont seem to be getting a decent temp in from them

engineermike

sheff the ref wrote: »

Basically a borehole has to compensate for the surface area that would be achieved by a horizontal collector to meet the requirements of a heatpump of a given size. I was involved with a job where there were 4 if not 5 boreholes and from memory I think they were 200m deep each.

I have specs somewhere for borehole depths needed for heatpumps with different KW. I do know at the time that collectors were being undersized in a bit way by different companies, and perhaps that has happened with boreholes.

The temperature from the heatpump should be relatively constant regardless of whether the collector was undersized or not. Basically the difference an undersized heatpump would make is that the pump keeps circulating the waterantifreeze working harder to get the temperature gain, hence drawing electricity and doesnt get much of a chance to cut out. That wouldnt really affect the temperature heading to the internal heating though I would have thought which should be roughly 40 degrees

As sheff has proposed this information is accurate - however if your not reading optimum temp differential at the pump computer (flow and return at the energy / loop - ground loop), there may be an issue with undersizing.
The manufacture of the pump & the KW of the unit (model no. also).
Distance from bore hole to inspection chamber and return to the pump.
Last time you had the unit serviced ?
These details would be helpful to provide an accurate answer of your probable issue.
Rgds,
Mike F

Condenser

hugo29 wrote: »

is there any way to determine what depth boreholes are. we have geothermal system but we dont seem to be getting a decent temp in from them

It will depend what the drill crew find when drilling. They should be checking the cuttings from the bore to check what type of ground they're in. A good rule of thumb is 50W per linear meter of pipe. What you're actually trying to do is cover the cooling capacity of the heat pump. The cooling capacity is the heating capacity minus the electrical load so if you had a 10kw heat pump with a 2kw electrical load you would have an 8kw cooling capacity. 8000W divided by 50W equals 160, so about 160m of bore would be required in this case.

If you're close to the above then your pipework could be too small. Your pump might not have enough pumping head. Was your borehole grouted? Are there filters in the line? Did it ever work right? Does it gradually drop and drop in temperature?

Also if you needed more than 120m and its all in one bore then that'll be a contributing factor. The pumping capacity required increases the deeper you drill and unlikely that the pump would be sized for that and the fluid would circulate slower. If drilling deeper than 120m it should be split in two. Below that is only suitable in commercial situations.

hugo29

engineermike wrote: »

As sheff has proposed this information is accurate - however if your not reading optimum temp differential at the pump computer (flow and return at the energy / loop - ground loop), there may be an issue with undersizing.
The manufacture of the pump & the KW of the unit (model no. also).
Distance from bore hole to inspection chamber and return to the pump.
Last time you had the unit serviced ?
These details would be helpful to provide an accurate answer of your probable issue.
Rgds,
Mike F

thanks guys, i am slowly going mad here

heat pump and bore holes were fitted in feb 2009

Model is Alpha Innotec, 14 kw

distance from bore hole to chamber approx 3m, distance to heat pump from chamber is approx 20m

bore holes were to be 100m each but that is debateable

they hit rock, limestone by the looks of the shavings at the time, no water found, holes were not grouted (did not know at time they should have been)

piping was 1 and half inch I think

system has never been right I think, and all I seem to get is muppets talking rubbish when i try to get it sorted, original plumber is gone bust which is a good thing really,

Condenser

hugo29 wrote: »

thanks guys, i am slowly going mad here

heat pump and bore holes were fitted in feb 2009

Model is Alpha Innotec, 14 kw

distance from bore hole to chamber approx 3m, distance to heat pump from chamber is approx 20m

bore holes were to be 100m each but that is debateable

they hit rock, limestone by the looks of the shavings at the time, no water found, holes were not grouted (did not know at time they should have been)

piping was 1 and half inch I think

system has never been right I think, and all I seem to get is muppets talking rubbish when i try to get it sorted, original plumber is gone bust which is a good thing really,

Theres your problem. Pipes are floating in mid air. You have no thermal contact. You need to get the bores grouted and then you should be fine. And make sure its done with a proper thermal grout.

hugo29

Condenser wrote: »

Theres your problem. Pipes are floating in mid air. You have no thermal contact. You need to get the bores grouted and then you should be fine. And make sure its done with a proper thermal grout.

ok thanks, next question,
1. who does thermal grout,
2. how much does it cost and
3. before hand is there any way I can stick camera down hole to see if it needs to be grouted for the whole depth, no point in grouting if dont need to

Condenser

hugo29 wrote: »

ok thanks, next question,
1. who does thermal grout,
2. how much does it cost and
3. before hand is there any way I can stick camera down hole to see if it needs to be grouted for the whole depth, no point in grouting if dont need to

Its a kind of how long is a piece of string question. You can calculate the volume of the bore to get an approximate volume of how much you need but cavities and fissures in the rock can affect this. Cost depends on who does it and finding someone is not an easy thing to do. Most drillers claim to do it but very few have the proper equipment. It should be grouted top to bottom regardless. You can get away with it if its sitting in moving water but you said yours is not.

hugo29

Condenser wrote: »

Its a kind of how long is a piece of string question. You can calculate the volume of the bore to get an approximate volume of how much you need but cavities and fissures in the rock can affect this. Cost depends on who does it and finding someone is not an easy thing to do. Most drillers claim to do it but very few have the proper equipment. It should be grouted top to bottom regardless. You can get away with it if its sitting in moving water but you said yours is not.

ok, can anyone recommend a company that they have experience with,

There is some water in bore hole but its stagnant i think and its a long way down

engineermike

Just a couple of points to consider also,
- The thermal grouting / bentonite is only going to lend itself in the order of a very small percentile of the efficiency.
- Depth of bore hole is more likely the latent issue.
Alpha innoTec 14.7 kW Heat Pump Mode SWC140s - Spec. is 2x no. 115m bore holes (max 10 m from manifold - although this relates to the circulation pump & the running time / cost to keep that pump over worked if it is).
Your pipe sizing sounds correct @ inch & half / '120m Double U-Probe 32mm PE 100 SDR 11 Pipe (x2)


The depth they achieved water in the bore holes sounds like the possible issue - less water / ground loop conductivity surface - thermal transfer surface - would adversely affect your Delta T.
A third ground loop would have amended this issue.
I'll P/m details so you can provide details to a competent engineer that will diagnose & repair.
mike F

hugo29

engineermike wrote: »

Just a couple of points to consider also,
- The thermal grouting / bentonite is only going to lend itself in the order of a very small percentile of the efficiency.
- Depth of bore hole is more likely the latent issue.
Alpha innoTec 14.7 kW Heat Pump Mode SWC140s - Spec. is 2x no. 115m bore holes (max 10 m from manifold - although this relates to the circulation pump & the running time / cost to keep that pump over worked if it is).
Your pipe sizing sounds correct @ inch & half / '120m Double U-Probe 32mm PE 100 SDR 11 Pipe (x2)


The depth they achieved water in the bore holes sounds like the possible issue - less water / ground loop conductivity surface - thermal transfer surface - would adversely affect your Delta T.
A third ground loop would have amended this issue.
I'll P/m details so you can provide details to a competent engineer that will diagnose & repair.
mike F

mike thanks for all that but you lost me a little, piping yes you are correct (blue have pic if required), bore holes if memory serves me correct were 100m each but i would have my doubts that they are even that

by 10m to manifold I presume you mean the external manifold and the distance to this from the boreholes, so at 3m I am fine

are you saying that a third loop in each of the boreholes is the best way to go, rather than grouting or both

when you say p/m details what does that mean

engineermike

hugo29 wrote: »

mike thanks for all that but you lost me a little, piping yes you are correct (blue have pic if required), bore holes if memory serves me correct were 100m each but i would have my doubts that they are even that

by 10m to manifold I presume you mean the external manifold and the distance to this from the boreholes, so at 3m I am fine

are you saying that a third loop in each of the boreholes is the best way to go, rather than grouting or both

when you say p/m details what does that mean

Its seems to be a combination of factors - but if your saying they unlikely achieved 100m depth in the bore & Alpha spec. says 115m, then your missing at the very least 1m per ground loop of surface contact area between the pipe and water source. Thats got to have an affect on the delta T.
What depth they achieved water at, again a contributing factor, lowering the surface area (Thermal conductivity area) in each ground loop.
Diagnosing the issue correctly is a must before a resolution / fix could be proposed.
Bentonite / thermal grouting, again a contributing factor - ( > %)
3rd loop / bore - is a 'possible' resolution, but better to diagnose the problem correctly first & then propose solutions to the issue.

P/m ( private message) - info. sent.
rgds,
Mike F.

sheff the ref

I suggest that the first thing you do is try and measure the borehole depth