Ground Source Heat Pump at Nowty Towers

[spread-tee]

Fittings are pretty variable in quality that's for sure, personally I solder all copper work,I only use compression if I cant use poly plumb or the pipework wont drain out enough for a solder joint.
Desp

Same here. Love a Yorkshire fitting and the smell of flux in the morning!

A friend convinced me to change to endfeed fittings: he said "If you can do a Yorkshire joint you can do endfeed, save a lot of money and space!"
I did and it has been OK. I was really surprised that when I disassembled one Yorkshire joint the inner end hadn't wetted / soldered the pipe at all, despite me being almost obsessive about cleaning both surfaces.
I have tried the "no need to clean" solder but didn't like it: it cleaned the copper perfectly but I couldn't assemble the joints. I put it down to the metal being so clean that it fused on first contact. I like the lubrication that you get with old-fashioned flux.
A

Same as that, yorkies have way too much solder in them for my liking, stalactites and snots galore, also when buying a couple of hundred quids worth you really feel the expense of yorkies. Also another bonus of end feed is they're easier to file the stop out of to create a slipper.

Desp

[nowty]

From a plumber selling up for £500, I picked up a brand new 300 litre stainless steel indirect hot water cylinder with a very large internal coil specifically for heat pumps. Internally it has 28m of 22mm corrugated stainless pipe rated at 57kW, about twice the amount of a standard cylinder. Also had twin immersions for my solar diverter too.




Decided to install it outside to be close to the heatpump and free up space inside my house.



And placed masses of insulation around it in fact there is now even more since that photo was taken.



Other pipes went through the wall of my house to connect up with my central heating system.



And zone valves were added so I could have either hot water or heating or both together controlled via WiFi sockets.

[nowty]

The heatpump has now been operating for 3 years, during this time I have had a few problems but so far non have been anything to do with the actual heatpump unit itself.

My main problem is silt build up on the under water copper pipe coils, this is usually only a problem in times of little rain in winter. The silt acts as an insulator therefore the cold circuit temp drops and if the return flow to the heatpump drops below zero degrees it shuts down. I can monitor the return flow temp from the controller in the house so I don't have to venture out to measure anything.




Silited up coils.



The remedy is simple, I give the coils a pressure wash for just a few seconds with a 2 meter lance so I don't even have to go down the manhole. The washing usually recovers the return water temperature by at least 2 degrees.




But if it rains hard then its self washing.

[nowty]

And the total cost for it all as a DIY job was around £3k, but a lot of work !

8kW heatpump (real world 6kW) - Ex-display but as new £1,000.
300 litre stainless steel heatpump cylinder with twin immersions - bought brand new from bankrupt plumber for £500
Bespoke home made copper ground source heat exchanger (heat extracted from underground water source) - £250
Water pumps - £300
Control valves, thermostat, etc, - £100
Pipe and fittings - £300
Additional radiators in house to increase efficiency. - £200
Timber, insulation, etc, - £200
Additional immersun (second hand) for diverting excess Solar PV - £200

Total - £3050

[nowty]

The other problem I have had is failures of the the external water pumps, about 1 per year but they are cheap and easy to replace. Generally easy to diagnose the problem but unless both failed on the same hot or cold circuit, the heatpump still runs, just less efficiently. Except for my recent failure where a failed water pump occasionally tripped the heatpump circuit breaker.

[Stinsy]

The other problem I have had is failures of the the external water pumps, about 1 per year but they are cheap and easy to replace. Generally easy to diagnose the problem but unless both failed on the same hot or cold circuit, the heatpump still runs, just less efficiently. Except for my recent failure where a failed water pump occasionally tripped the heatpump circuit breaker.

I get installing cheapo pumps to get the thing running. Do you think an upgrade to ultra-reliable, more-efficient, circulation pumps would be a worthwhile project?

[Joeboy]

The heatpump has now been operating for 3 years, during this time I have had a few problems but so far non have been anything to do with the actual heatpump unit itself.

My main problem is silt build up on the under water copper pipe coils, this is usually only a problem in times of little rain in winter. The silt acts as an insulator therefore the cold circuit temp drops and if the return flow to the heatpump drops below zero degrees it shuts down. I can monitor the return flow temp from the controller in the house so I don't have to venture out to measure anything.




Silited up coils.



The remedy is simple, I give the coils a pressure wash for just a few seconds with a 2 meter lance so I don't even have to go down the manhole. The washing usually recovers the return water temperature by at least 2 degrees.




But if it rains hard then its self washing.

I remmeber some of these photos from the old place. There is still a sense of awe at this project, well done!

[Stinsy]

I keep thinking to myself: "I wish I had a river running under my house". But then I remind myself that this was: "making the most out of a *BAD situation* in heroic fashion". Emphasis on the "bad situation".

[nowty]

The other problem I have had is failures of the the external water pumps, about 1 per year but they are cheap and easy to replace. Generally easy to diagnose the problem but unless both failed on the same hot or cold circuit, the heatpump still runs, just less efficiently. Except for my recent failure where a failed water pump occasionally tripped the heatpump circuit breaker.

I get installing cheapo pumps to get the thing running. Do you think an upgrade to ultra-reliable, more-efficient, circulation pumps would be a worthwhile project?

Maybe, the pumps are actually not the cheapest and are an efficient shaftless design. After a couple failed, partly my fault because of using them on the cold circuit without insulating them, I bought a job lot of them so I still have 3 spare. The ones on the hot circuit have been fine so I might just replace the cold circuit ones.

[Gareth J]

Great write up, thanks for taking the time, again. Particularly for sharing the rule of thumb maths you used too.