Ground Source Heat Pumps

lovesgshp

These are what I mean as the collectors, the 2 horizontal black tubes on the right of the picture. On the lower one is the pressure valve, the upper has the air bleed, plus the pressure guage.
It is my house installation, but ignore the orange buffer tank, as that is no longer there!!
http://www.geotherm.it/esempi_impianti_progetto_15_geotermia.html#1

beardymarrow

lovesgshp wrote: »

These are what I mean as the collectors, the 2 horizontal black tubes on the right of the picture. On the lower one is the pressure valve, the upper has the air bleed, plus the pressure guage.
It is my house installation, but ignore the orange buffer tank, as that is no longer there!!
http://www.geotherm.it/esempi_impianti_progetto_15_geotermia.html#1

Yeah, we're looking at the same thing then. Those 3 pipes in the picture in my post (I guess you could call it a manifold, of sorts) are the output to the ground loops. There's no gauge or air bleed valve. There's just the expansion tank (vertically above the HP) which then leads through the filter to the pressure release valve and trhen that set of 3 blue valves and pipes in the picture. The return 3 pipes just go through the same type of valves and connectors and back into the HP.

lovesgshp

If you still have the engineer coming on the 11th, then a couple of questions you need to ask in regard to the ground loop, as you do need to be able to check the pressure in it, as that effects operating.
1) Lack of pressure guage, as the loop needs to operate at circa 0.5 bar.
2) There should also be a valve inlet from the mains water feed to boost the above pressure as required. (yellow hose in the pic I supplied, is from that connection).
Please keep me updated, as glad we found the source of the problem.

beardymarrow

Thanks. Will do.

Quick update. Electricity usage has dropped quite a bit, although it's not as dramatic as I'd hoped, however obviously I have changed the heating to higher values as well, by upping the heat curve.

Electricity usage for a day before the 3-way was unstuck


Usage today, after it was unstuck

So, you'll see that the peaks are a lot shorter. However, it does seem to need to re-heat the water very frequently. Might this be because we have a hot water recirculation pump? I need to look at the timer it is on to see what times it is on for to see if that corresponds.

So, as I need to now change one thing, and one thing only, do you reckon I should set the heating back to how it was, or turn off the hot water re-circ pump first?

Cheers

lovesgshp

Hi.
Not sure what you mean by the hot water circulating pump, can you please explain.
Try the heat curve at 3.5 and see if you are happy with that level, although I do suggest the default level are set at factory, as per the simulator.

beardymarrow

lovesgshp wrote: »

Hi.
Not sure what you mean by the hot water circulating pump, can you please explain.
Try the heat curve at 3.5 and see if you are happy with that level, although I do suggest the default level are set at factory, as per the simulator.

Hi,
I mean there's a pump (a normal central heating type pump) on a timer (not sure what times it's set for, but I will check), that pulls hot water from a pipe under the furthest tap in the hot water circuit and pumps it back into the cold inlet of the tank. This is so that there is instant hot water at the taps, shower, etc. with no delay. It's designed so that you don't have to wait for the tap/shower to warm up, and also therefore saves water, but I'm wondering if passing water through the pipes cools it so much, and that's why my DHW is having to re-heat the water so often.

http://en.wikipedia.org/wiki/Circulator_pump#Use_with_domestic_hot_water

For a D300/160 DHW tank (without recirc), set at 51deg, how frequently would you normally expect the GSHP to have to cycle on, to heat it back up to temp? From the graphs, mine seems to be on for 30Mins, off for 20Mins, etc. (this is overnight when there is no DHW draw).

Before the 3-way was fixed it was on for 1Hr40Mins and off for 20Mins (for the same time of day), so we've still made massive progress.

I just don't understand how it's dropping from 54 (which is what it heats to), to below 51 in 20Mins, unless it's the recirc. I guess the only way is to try it with it switched off.

lovesgshp

We have never in my experience put such a unit in. The pump would normally just supply hot water on demand. It may take a little while to reach the furthest from the DHW tank, but that would be accepted with a normal system.
The 300 ltr tank on normal operation, should be on for a very short time to boost the hot water back to the 51C level, as it would normally switch back in @ 48.9C.

beardymarrow

lovesgshp wrote: »

We have never in my experience put such a unit in. The pump would normally just supply hot water on demand. It may take a little while to reach the furthest from the DHW tank, but that would be accepted with a normal system.
The 300 ltr tank on normal operation, should be on for a very short time to boost the hot water back to the 51C level, as it would normally switch back in @ 48.9C.

Thanks. With the recirc I can literally get in to the shower on the 2nd floor (HP and DHW tank is in the basement) and switch the water on while stood under it and it's immediately the right temperature. I'm prepared to forgo that luxury if it's costing me a fortune in DHW production though .

By very short time, what are we talking about? The HP coming on for 5 mins every hour, something like that (assuming no usage of DHW)? I just want to know what I'm aiming at, so I'm not chasing the impossible. Of course I know some of the on time might be because the ground loop isn't up to pressure, but the off time should still be OK.

Yes, mine comes on at about 49, and goes off at 54C.

lovesgshp

Yes, it is probably that pump causing the problem. If you can wait a minute or so for the hot water, then it is not needed in the system.
By short time, I mean about a minute or so. I have a client with the 300ltr tank, who only has it operating for a couple of hours a day, but it may be their lifestyle. Mine is 160 ltr, but the operating times are only about 1hr or so a day. Without rechecking, it gets from 46C to 52 in about 5 to 6 mins.

Fly100

lovesgshp wrote: »

Welcome to the forum.
You do not say if it is underfloor or radiator heating. If UF then I would honestly not bother with the heatstore.
Forget the solar water heating, you will not save anything in reality. DHW production should be circa 20% of the pump operation over a year.
HTH

Going under floor downstairs and Rads upstairs.


Im only wanting to add the Wood Stove as a back up as I get cheap wood and I really don't fully trust the GSH as yet. I like a warm house....


Thank you for the info.


FLY