GSHP pipework & ground frozen SOLID 1 metre UNDER ground

[fingertight]

Hello all

A mate of mine called me today, he is repairing his gaffers ground source heat pipework (cost £12,000 to install 6 months ago) its in a biult up area (four oaks-sutton coldfield).

The thing that threw me was that he said the frozen pipework is 40mm size, and is 1 METRE under ground, all the material around the pipes is frozen solid also??? THE TOP SOIL LAYER IS NOT FROZEN?? dig down a metre and he has had to KANGO the area due to it being frozen.

I thought the average temp at that depth is around 9 to 10c no matter what the season?? How could it all freeze solid at that depth??? Unless it is ULTRA efficient and has sucked the heat energy out of the ground around it to the point where it froze? I have not installed GSHP but shouldnt it have a frost stat?

Any words of wisdom on this would interesting to hear

 

[Corgigrouch]

Ground loop not long enough or too close together for the size of load..... Call the installer back.

 

[fingertight]

Thanks ill let him know...I didnt ask why he never called em back in the first place?

I still dont understand how it can be ok on top soil..and frozen 1 meter under? It should be a constant 9c?

 

[Biggles..]

bad install,the loop has drawn all the available heat out and created a frozen area.

check units running right but suspect loop to be incorrect in spacing and length

if flat lay would expect 1.2m deep, 1.2m centres, average area 25sqm per kw.

if slinky then im not surprised.

 

[fingertight]

cheers lads, thats fasinated me, as I thought, so its the pipes that have frozen the ground, not the ground frozen the pipes..wow.

 

[Corgigrouch]

You would have to have a Winter a damned sight colder than we have had and for a long time to freeze down to 1meter.... Yep your ground loop has frozen the ground... Has the heating been struggling to heat the property?

Here is a thought for the GSHP designers, why not use solar panels to heat the ground in the Summer so that the ground can be used as a heat store to help in the Winter.... We do have more than enough solar energy to heat all our years supply of water but can only benefit from what we can store and use in cylinders in the Summer, why not dump the rest of this energy in the ground where we can use it later... Perhaps someone already does this?

 

[ianniann]

Run the heat pump for cooling in summer, that will dump a load of heat into the ground

 

[Nige F]

I had a dump in the grounds of my estate . The earth storing heat from summer all through to winter WOW that`s like magnetically altering petrol to improve fuel economy

 

[ianniann]

I'm not sure if you're actually being sarcastic about this Nige, but ground source heat pumps most definitely use heat stored in the ground from summer to winter. That is why it is constantly near 10C once you get more than a few feet deep. If you can find an effective way of getting large quantities of heat down to that level in summer then it will certainly still be warmer in winter. Likewise if you extract all the heat in winter by overloading it with a heat pump then it will stay frozen for many months.

I don't think the heat storage idea is really that viable because of the expense of getting such a large amount of heat down to depth, and because the temperature increase involved is likely to be small so the heat pump efficiency will hardly improve. Still, if you do need cooling from a ground source heat pump then it's nice to know that the excess heat is actually helping you in the winter.

 

[htgeng]

From the OP's post, I think there a few points of concern.

If the job had been done by professionals then they would have put antifreeze in the ground loop, so the liquid wouldn't have frozen solid.

If the guy is going to kango the entire loop up hes going to be there for a long time or was that just a test hole to see whats happened?

As the others have said, it sounds like the loop hasn't been installed correctly - possibly by jobbing builders who thought they'd have a go at it.

Reading between the lines I'd say the £12,000 was almost nearly the cost of the heat pump and the pipes were just dug in by a guy with a jcb and not correctly designed. Maybe they just dug a few adjacent trenches and threw in some leftover mdpe. They filled the ground loop with tap water.

 

[Biggles..]

Ground loop....antifreeze.....I'd have thought brine

it's not the pipe and content that freezes(have you ever tried to freeze hdpe,it's bloody hard with out cryo) it's the ground mass around the pipes that freezes.

 

[DeltaT]

Slinky's are shyte and it does sound as if there's not enough ground loop!!

Aah yes, the Greenwash ex-Double Glazing salesmen strike again!!

£12K!!!............Never laughed so much since the wife died!!!

When will we ever learn in this country? GSHP's have been around for years & yet we always end up with hard sell ex-used car salesmen chancers & cowboy installers & it's all taxpayers money!!!

 

[mysteryman]

You do not get something for nothing in this world. Ground collectors need careful design, and the green credentials are only really green if you power the heat pump with green - wind, water, or solar - electricity. Using grid electricity to power a heat pump is ludicrous.