GSHP pipe

[David_Jones]

Hello, With Ground Source Heat Pumps why are the long coli type pipes (slinky) so expensive ?. Why can't I use regular water pipe of the same diameter?......is it the material, structural needs or what and most importantly why?. I be grateful for any information.

 

[snowhead]

Just googled for you and it appears the Coils are formed to stay in shape in a Slinky whereas in a regular coil of MDPE the coils are a by product of production and will try and reform when you unroll it into loops as needed for a GSHP array

 

[Worcester]

Additionally they have specific requirements to prevent penetration of stones etc (you want close contact with the soil), they have a specific minimum Reynolds number (roughness inside the pipe to get turbulent flow) and also they specific thermal properties top transmit the heat from the soil into the glycol mix, to name just a few... Compared to the excavation and laying costs, the pipe isn't expensive.

Also if all possible and you have the space, DON'T use slinkies, straight ground loops have far better performance, and cause less problems than slinkies. (You'll still need special pipe though )

 

[Howsie]

Hello, With Ground Source Heat Pumps why are the long coli type pipes (slinky) so expensive ?. Why can't I use regular water pipe of the same diameter?......is it the material, structural needs or what and most importantly why?. I be grateful for any information.

Are you an engineer by chance David?

 

[Ermintrude]

Just use some off Cuts of 10mm speed fit!

 

[Nostrum]

Hose pipe will do it

 

[gassafe]

Along with the budget heat pump your looking at on eBay I'm sure it will be a real quality job !!

 

[Ermintrude]

Can't u drill into water table and use that as a massive heat unit? Below the thermoclimb? I heat my house with waste water heat..... Was a right mess running in 3000m of 15mm in next doors sewer!

 

[David_Jones]

Thanks to all for the replies. I have built my houses from plot to completion over the years, on the third at the moment. The third house has good energy saving stuff by using the 'Best available technology but with out exceeding silly cost' formula. Just at the moment i need to work out the best heating source for my central heating hence the ASHP pipe question. I had a verbal quote that a GSHP with cost about 20K.....i almost fell off my chair. So I have started to see how I can get the GSHP cheaper (the self building way I suppose). I need to get some feel for the lost efficiency if all I changed was the typical 'slinky' pipe for a water pipe . Would it loose 10%, 25%, 50% or more ?. I feel if i built my own 'good enough' system it world come in wayyy under 20K and possible enjoy the work .......my thoughts are - non grant system (did the grants ever get paid?), fit it myself useing non building regs materials if i have to such as top soil to protect the pipe etc. . PS - I forgot to mention I live on the Isle of Anglesey are we tend to get milder temperatures in winter than that of central UK locations (-10 degrees difference is not unusual in the middle of winter) so the heat that I will need may not be as brutal as some other GSHP loadings. Thanks again, David

 

[Worcester]

As a self builder, you would be eligible for the Domestic RHI

If you try to do the self install route you won't be eligible for the RHI, as it won't be an MCS certifed insatllation.

Seeing as a GSHP pays nearly 3 times what an ASHP does over the 7 years under RHI, on a new build a GSHP is a no-brainer, designed properly (in conjnuction with designing the heating system) it offers a far better return on investment and it will also cost you less to run than an ASHP.

Seems like you need professional advice this time round as the game has changed. There are some many mistakes to be be made with GSHP's that's why the RHI regulations REQUIRE you to use an MCS registered company. No if's, no buts, not shortcuts, it has to be done properly.

Ask anyone that has tried to do even a SolarPV system themselves and they'll tell you that the amount of information and variables that you need to learn and consider, that for the next time and for anyone else that asks their advice is simple - use an MCS certified installer !!!

If the people you spoke to couldn't show you either the return on a GSHP or the comparison with an ASHP then you're talking to the wrong people.
This is bread and butter stuff for us.

 

[eaton]

According to real time examples there isn't a huge run cost differance between Gshp and ashp now, everytime I've looked at quieting Gshp it goes no where just on cost of ground side to start with, issue is units are similar in price but ground works make it too expensive for most, rhi payments do make it more viable but its initial outlay that puts most of and towards ashp. Lot less to go wrong with ashp too and much cheaper fix if it does,

 

[Nostrum]

Look at it the other way, you could spend £10k on a system that doesn't work or is likely to fail in the future.

if your going to be living in this house yourself, as Worcester has said, you'll be far better off using an MCS installer, getting the RHI payments which are generous and having a well designed system or at the very worst having someone to blame if it doesn't work as required! ( depending if you go for the cheapest quote or the company that has the correct knowledge)

 

[Worcester]

DRHI pays 18.8p/kWh of renewable heat, for GSHP and 7.3p/kWh of renewable heat for ASHP, in general GSHP 25% more effective than ASHP, therefore IF you've got the capital GSHP stacks up financially as the DRHI will pay you back more.

Take a building for which 30,000 kWh per annum is payable, run both at 45° as example, under the DRHI
ASHP will earn £10,220 over 7 years
GSHP will earn £28,810 over 7 years

Plus running costs long term for the GSHP will be that 20-25% less than with the ASHP.

 

[David_Jones]

Hello Worcester Renewables, Do the money amounts mentioned above actually get paid now? , Thanks, DJ

 

[Ermintrude]

Gshp every time. Pays more works better

 

[Worcester]

Hello Worcester Renewables, Do the money amounts mentioned above actually get paid now? , Thanks, DJ

Hi DJ, if you are not on Gas you would be eligible for an initial lump sum payment (RHPP) of £2300 , this would then be deducted in 1/28ths from the future RHI payments (4 payments per year for 7 years ie 28 payments) which are scheduled to start in Spring 3014. If you do have mains gas then you don't get the RHPP and so the quarterly payments are slightly higher ( no deduction to make) these quarterly payments would start as above.

 

[SimonG]

Hi DJ, if you are not on Gas you would be eligible for an initial lump sum payment (RHPP) of £2300 , this would then be deducted in 1/28ths from the future RHI payments (4 payments per year for 7 years ie 28 payments) which are scheduled to start in Spring 3014. If you do have mains gas then you don't get the RHPP and so the quarterly payments are slightly higher ( no deduction to make) these quarterly payments would start as above.

You might just be right with the year there (3014)

 

[SimonG]

Sorry! Couldn't resist

 

[Howsie]

Hello Worcester Renewables, Do the money amounts mentioned above actually get paid now? , Thanks, DJ

But only if it's MCS'd and that won't happen with hose in the ground.

 

[eaton]

Your eligible for rhpp and rhi grants/tarrifs if your on or off grid now

 

[Nostrum]

Unless you need the RHPP money to get going I wouldn't bother claiming it. The RHI payments are index linked so the more get in the future the more likely you are to gain from inflation.

 

[David_Jones]

Thanks for all the replies. Does any one have the link where this information is shows?.. the people who pay so I can phone and ask. The Government site?. I be grateful again, DJ

 

[Ermintrude]

https://www.gov.uk/government/polic...supporting-pages/renewable-heat-incentive-rhi

 

[Worcester]

Here's they key document https://www.gov.uk/government/uploa...file/212089/Domestic_RHI_policy_statement.pdf