Ground Source Heat Pumps

matelodave

I'm all in favour of going green but paying 5p/kwh extra for 7200kwh for the privilege would cost me over £350 a year which I'm sure you'll agree is not really viable.

poohbear59

One of the reasons that we have 100% renewable is that we have a gold award for green tourism, and we strongly believe that we should do all we can to have as little environmental impact as we possible. I heard about another tariff that Octopus offer that may be better for us. I am currently researching tariffs. You have certainly made me think. It is a huge impact on our pockets. We have had 100% renewable electricity for as long as it has been available, so have spent a huge amount on it over the years. 

Patrol

poohbear59 said:

The cottage has no heating or temperature controls.

On my IVT I can see the room temperature can be viewed and adjusted via menu 1.10. I have room thermostats in three bedrooms but these are linked to the underfloor manifold rather than the heat pump.

poohbear59 said:

The add heat is on every day. 

Add heat being used daily is not good, there could be several reasons for this:
- Physical installation issues
- Sub-optimal / cautious setup within the heat pump settings
- Heat pump undersized for the property

Is the add heat for heating or hot water. You may be able to check this, for mine I can see this in menu option 7.4 (a number of menu options are hidden but then become available if I press and hold the "Menu" button for 10-15 seconds). It's a pain for me to access the settings now as the scrollwheel on my unit needs a lot of scrolling before it moves and often then jumps two or three settings at a time or in the opposite direction to which I am scrolling.

If the 7.4 setting shows a high percentage for DHW domestic hot water, what do you have for these settings:
- Menu option 4.3, set how water to clock. Mine shows "off" so the Mon-Sun times aren't used and it can heat 24/7
- Menu option 2.3, hot water temperature. Mine was 51 degrees initially but now 48 degrees
- Menu option 2.2, interval for hot water peak. Mine was 7 days, we had quite a discussion here and now set to 30 days as per guidance from @lovesgshp

Regardless of whether the use is for hot water or heating, I would also check menu setting 8.1 setting additional heat timer. Mine was originally set to 60 minutes and I increased it to 180 minutes. What I think this did was allow the ground loop to be used for 3 hours before any additional heat was used. I'd rather have the ground loop running for longer and the additional heat being used sparingly. Before I changed it the unit might be off for an hour then run for an hour then run with additional heat for something like 20 minutes, then repeat that cycle. After the change the unit ran for longer but without additional heat.

If you are able to find this level of information and share it here it may help in understanding if anything can be done to reduce your costs.

beekeeper2003

Good evening. I bought my current house 3 years ago and have never bothered with the heat pumps (two IVT Greenline HT+ 9 Kw pumps) apart from lowering the heating temperature setting,cleaning the filters and making sure the pressure is 2 Bar plus. Recently I tried to add some pressure to one of the pumps (HP1) but it would not move the dial which seems odd (the dial is fine, I'm pretty sure). Could this be a sign that the 3 port valve may not be operating correctly as that seems to effectively be underneath the pressurisation point  and sometimes the bedrooms seem much colder than they used to ?  This has caused me to take more interest generally, and I have logged all of the Menu 3  readings as below. It also seems to me that the GT11 sensor on HP1 must have failed - is this of any consequence I wonder ? Finally, the outdoor temperature difference between the two pumps looks a little odd. It is currently minus 1 outside and both loops are adjacent to each other so the large differential between them seems odd ?  Any thoughts/comments greatly appreciated as I am trying to get my head around how these all hang together.

	Readings circa 6.45 pm 30/01/21
	HP1	HP2
	Beds, Utility, Study	Sitting Room  Dining Kitchen
GT1
Off	32.9	30.4
Now	31.7	26.1
GT2	1.4	6.8
GT3
Target	51	51
Now	52.1	56.7
GT5
Target	18.5	18.5
Now	18.8	19.1
GT6	75.3	72.9
GT8	42	36.4
GT9	32.4	27.2
GT10	0.3	0.9
GT11	97	-2.8

beardymarrow

Hi beekeeper,
Don't worry about the outside loops (GT10 and GT11) being different temps, that would be perfectly normal and depends on the load on each unit (as well as the ground temp). It's the delta between GT10 and GT11 that is important, and that looks fine for HP2. For HP1, yes it looks like your GT11 sensor is knackered. That won't cause a problem in itself, but it will mean that your HP is not able to react to an under temp on the output side, so you could have a problem and never know until it causes a big failure. Get it replaced :-)
Regarding the outside air temp (GT2) that difference in temp does seem odd, but then it depends on where the two sensors are mounted. I'd suggest one is in sun and the other in shade normally, but not at 6:45pm :-) Do you know where they both are, and are they next to each other? Is one in a windy spot or something?
When you say you tried to add some pressure, on which side was this (hot water side to your radiators, or the cold side to the outside)?
Finally, are the two pumps completely separate from each other? I would assume that they are.

beekeeper2003

Beardymarrow. Thank you very much for your reply which I have only just seen - I must bookmark the forum (I lost it !) and check it more often. The two sensors are adjacent to each other on an outside wall but within a wooden box that is open at the bottom but covered on the roof & sides. The pressurisation is a cold water feed that connects to the heating system return judging from the diagram in my manual of what the pipes are that go into the unit.  The two pumps are wholly separate units though I think the two hot water outputs join together outside the units whilst each pump does different floors for heating. I have now received the new sensor I ordered and shall try to fit this later.  On the pump with the faulty sensor, where there are gaps in the insulation on the ground loop pipework, there is a build up of ice (picture attached).  I propose to try and improve the insulation if I can do so but is this normal or a sign that the unit may be undersized and is working too hard ? Many thanks for your help. I am trying to improve my knowledge and am eagerly awaiting two Husdata H60 interfaces that I have ordered.

beekeeper2003

A follow up - I have successfully changed my GT11 sensor - I wouldn't have contemplated doing this myself without the help/confidence provided by the  forum so many thanks to all contributors. However, after turning the heat pump back on, I was perturbed to see the Hot Water temperature showing a target of 51 but rise steadily to reach just over 65.  I've checked Menu 2 and there is only the additional hot water 2.1 setting showing in this menu and it is showing 0 hours so it doesn't appear to be that. Presumably, it must have been the pasteurisation setting ?  Where would I find that and is it possible to adjust when it occurs and the temperature it takes it to ?

beekeeper2003

And more ... have now worked out that to find the additional settings in Menu 2 you need to be in service mode which I've now done. Both pumps are set to pasteurise every 7 days which I think is probably OK. So really just the icing up and pressurisation that I've still got to get my head around.

beardymarrow

beekeeper2003 said:

A follow up - I have successfully changed my GT11 sensor - I wouldn't have contemplated doing this myself without the help/confidence provided by the  forum so many thanks to all contributors. However, after turning the heat pump back on, I was perturbed to see the Hot Water temperature showing a target of 51 but rise steadily to reach just over 65.  I've checked Menu 2 and there is only the additional hot water 2.1 setting showing in this menu and it is showing 0 hours so it doesn't appear to be that. Presumably, it must have been the pasteurisation setting ?  Where would I find that and is it possible to adjust when it occurs and the temperature it takes it to ?

Good work! There's a few things to bear in mind with the DHW.
1. The target has a hysteresis on it, by default 4 deg, so it actually allows the DHW to drop to 2deg below the target and go to 2deg above the target before switching off. This is in 2.4. I have changed this to 2deg on mine as I think 4 is too much, and left alone it takes approx 12Hrs to drop those 2 deg, so I see no reason for it to be 4.
2. The DHW actually switches off depending on the GT9 temp, not GT3x as you might assume. GT9 will lag GT3x.
3. Once the DHW switches off, the temp will continue to rise for a little while as the coil will still be hot.
The combination of the 3 things above mean that for my DHW target of 50degC, I have peaked at 55.8 in the last 24Hrs. That doesn't seem to account for your difference, so I assume it is Hot Water Peak.
4. There is a pasteurisation setting. This is called "Hot Water Peak" and will increase the DHW by 5deg every week (if it's set to 7 days). This is in Menu 2.2 (in Customer Level 2). Go to this by pressing Heat button until it says CUSTOMER2. I have this switched off on mine as I am using DHW every day, so no need for it in my opinion. Useful if the DHW was only used intermittently.
5. You have "additional hot water" that you can request for up to 48Hrs which increase the temp of the DHW to provide more hot water (if you visitors and will have a high demand, for example). Not relevant to this situation as you've checked this in 2.1

beardymarrow

beekeeper2003 said:

Beardymarrow. Thank you very much for your reply which I have only just seen - I must bookmark the forum (I lost it !) and check it more often. The two sensors are adjacent to each other on an outside wall but within a wooden box that is open at the bottom but covered on the roof & sides. The pressurisation is a cold water feed that connects to the heating system return judging from the diagram in my manual of what the pipes are that go into the unit.  The two pumps are wholly separate units though I think the two hot water outputs join together outside the units whilst each pump does different floors for heating. I have now received the new sensor I ordered and shall try to fit this later.  On the pump with the faulty sensor, where there are gaps in the insulation on the ground loop pipework, there is a build up of ice (picture attached).  I propose to try and improve the insulation if I can do so but is this normal or a sign that the unit may be undersized and is working too hard ? Many thanks for your help. I am trying to improve my knowledge and am eagerly awaiting two Husdata H60 interfaces that I have ordered.

I assume from the picture you mean the cold side (to underground), not the heating system (the rads in your house). I wouldn;t worry about the pressure on that being below 2Bar, you've got the expansion vessel anyway. The ice build up is normal too. The cold out to underground will regularly be below freezing, so this is just condensation freezing. Insulate it, for definite to reduce that, but I wouldn't worry that was a symptom of a problem (other than lack of insulation).
The critical thing is the GT10-GT11 delta, which should be 2-4deg and GT8/GT9 (7-10deg). If it was undersized, this delta would be too low. If you've got a blockage or too low flow it'll go too high.
For HP2 the values you have written above are spot on. Obviosuly I don't know for HP1 as your GT11 sensor on that one was knackered when you read them. What are they like now (let it run for 5 mins producing heat before reading).

Lastly, IMHO Husdata is worth it's weight in gold. I've got the previous model (H10 IIRC), and it's brilliant