Water Source Heat Pump Project

[nowty]

Nice job!!   
I like the use of coloured cable ties for identifying the flows, I'm going to replace all the bits of scribbled-on tape now.

Ah yes I should have provided a key,

Red = Hot Water
Blue = Cold Water
Yellow = Heating Flow
Green = Heating Return
Red/Blue = Pre heated water from unvented tank as it could be hot or cold.

[nowty]

My main point in posting relates to the inevitable narrowing of E7 prices as time goes on. It doesn't take a genius to work out that as more use is made of cheap E7 rate electricity the cost will go up thus reducing the level of savings we all carefully calculate in advance as part of the argument for making the changes we do.

Yes, in the past E7 night rate used to be less than half price but now it is normally more than half price and usually with high standing charges.

I suspect that in future with more Solar in day, expensive Nuclear plants come on stream, more overnight use for domestic batteries and EVs it might narrow even more. But I think we will inevitably be in a situation where peak early evening costs will be prohibitably higher making domestic batteries possibly viable for the masses even if you don't have any PV.

[nowty]

Project Update


I have yet to wire up the thermostats, etc, but I tested the heat pump today with all the plumbing complete and solely powered by PV with the autumn sunshine on both my new hot water tank and my central heating.




Works fine, ran it constantly for 3 hours, first heated 300 litre tank to about 50 degrees in around two hours and then I ran it on the heating circuit and house was very toasty. All radiators heated up to 35 degrees in little time.




Ground loop stayed several degrees above zero throughout and difference in flow and return temps for both ground and heating loops was 4 degrees.
So ground loop is big enough, water pump size is ok and I definitely do not need a buffer tank. Very happy.

[biff]

Well done Nowty,
            This is a great help to the members like me who are considering like minded projects.
                                                Biff

[Nickel2]

Great Admiration! When life gives you lemons, forget lemonade, hold a cocktail party. I'd love to be in your position, but without the pre-courser stress of using your house foundations as a surfboard on the River Styx.
My your sun shine bright and your river flow clear for ever!

[todthedog]

A fantastically​ interesting thread.
An example on how to turn a potential disaster into a long term benefit.
As well as having us on the edge of our seats along the way.

[offthegridandy]

Thanks for sharing all  this and brilliant result.

[desperate]

A fantastically​ interesting thread.
An example on how to turn a potential disaster into a long term benefit.
As well as having us on the edge of our seats along the way.

Same as that, had me bricking it when you were underground, but    ....nuff said

Desp

[nowty]

Project Update

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree or so after 12 hours even if its cold outside.




Hot water and heating can now be operated with WiFi sockets via my smartphone.
WiFi socket turns on a zone valve which turns on the heatpump if thermostats request demand for heat.
So can use timers and countdown timers with ease.




As there is not enough PV leccy at this time of year I have been using it daily for 4 hours overnight on economy 7 for over a month now. It keeps house warm for the morning and we get a full tank of hot water. The gas boiler takes over the heating at 7:30am but because the house is already warm, it only comes on very low which seems to run more efficiently as gas consumption is significantly down, more so than I expected.

I will report back after I have a year of data to show how much total energy import has been saved.

[marshman]

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree of so after 12 hours even if its cold outside.

Interesting. My tank drops about 2-3 deg per 24 hours (and that is indoors!). It is a 300 ltr Joule. Don't think it is losing it through the pipes so I was considering adding more insulation around it. How much "extra" insulation have you put round yours?

Nice install by the way!

Roger

[nowty]

Hot water tank and pipes now fully insulated.
Temperature of tank only drops a degree of so after 12 hours even if its cold outside.

Interesting. My tank drops about 2-3 deg per 24 hours (and that is indoors!). It is a 300 ltr Joule. Don't think it is losing it through the pipes so I was considering adding more insulation around it.

How much "extra" insulation have you put round yours?

The tank is pre-insulated with 5cm of foam.

Then its boxed in on three sides and top by 5cm of celotex foam board. Corners of the box are filled with a hot water jacket panel. And several more jacket panels wrapped around the open side. With remaining gaps filled with some other bits of insulation.

If you place your hand between the jacket panels and the tank it feels warm as toast. Where as with only the tank insulation, the external parts of the tank would normally feel cold. So the extra insulation is certainly helping.

[marshman]

Thanks for that info. I'm going to have a go at mine. Its a bit hard to get much down the back and on one side as it is close to the wall, but I'll pack in as much as I can and see what difference it makes. To be honest I am not overly impressed with the new tank in terms of heat loss. The old tank (copper with sprayed on foam - 30 years old) seemed to lose less heat - often stayed hot for 3 days, never seem to manage more than 2 with this tank. Pipe work is the same.

Roger

[nowty]

Quick update.

Everything has been working well but I have found one problem.

A few days ago I noticed that the ground loop was getting colder, a lot colder, dropping from above zero a couple of weeks ago, down to minus 8 or so but it was still working fine.

A day or so later the heatpump cut out a few times with low ground loop temp error and it was getting down to around minus 12 which is near the limit of my anti freeze solution.

I thought it might be game over until the river water temp rises again, its currently at about +8 degrees and wont rise again till around March.

I checked the river heat exchanger, expecting to see a block of ice but it was actually caked in silt so it was just insulating the copper from the water.

I knew the forecast for the following day was heavy rain so I just left it and it all cleared away by itself, all working again with return ground loop at +7 degrees.

So should work all winter but I will need to occasionally pressure wash the silt off if it does not rain for a while. Its a bit of a pain as I hoped it would all be maintenance free but at least there is no fundamental problem with it.

[knighty]

could you block/restrict the flow a little around the coils?

that way the water will flow into a smaller space and speed up... (same litres through smaller space) - the extra turbulence should.might/could clear the coils?

[nowty]

could you block/restrict the flow a little around the coils?

that way the water will flow into a smaller space and speed up... (same litres through smaller space) - the extra turbulence should.might/could clear the coils?

Not really.

I am going to install a remote temp sensor so I can keep an eye on the ground loop temp so I can easily see when its starting to drop too much. Its not something that happens quickly, only slowly over few weeks of little rain.