Ground Source Heat Pumps
Comments
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With the hot water hysteresis on the HT series pump, then GT3 decides the start temp, but GT9 the shut down. This is why you tend to get the higher reading in GT3, than the hysteresis.
Ah, that explains it, then :A! This has been bugging me for a while. I've checked through my H10 stats and this is exactly what mine does.
GT3 Tgt is 52c, hysteresis of 4.
Compressor switches on when GT3 drops below 50c and switches off when GT9 goes above 54c (GT3 usually around 56.5 to 57c).
Now all I need to do is to figure out why my hot water peak isn't cutting in :think:. I think I'm going to change it to daily and then turn off the DHW blocking overnight to see what happens. If that works, I'll re-instate the block, and then if that doesn't work I'll set it to weekly and re-instate the block (except on the day it's supposed to do the peak). I know the block shouldn't matter as it should cut in next time there's a DHW heat cycle, but I'm not getting the hot water peak at all.0 -
Anyway, the DHW expansion vessel has a 6 bar pressure valve. I noticed at the end of the heating cycle that about 4 drops a second were produced. I had to go out, coming back 2 hours later I saw it was still dripping about once every 7-10 seconds. Does that sound right - my borehole is set to just over 3 bar if that is relevant and that was based on the original advice re the GSHP.
It could be a faulty valve, but as no pressure gauge, it is hard to tell, as you cannot see what is happening, or reduce the level.beardymarrow wrote: »Tried the ground loop at Speed 2 for a couple of days now, and no alarm.
Here are the temps from a recent DHW heat cycleTime GT10 GT11 GT3x 06:57 22.8 22.7 49.6 06:58 14.6 20.5 49.6 06:59 9.5 10.1 47.9 07:00 7.7 5.6 47.9 07:01 7.1 4.1 47.9 07:02 6.8 3.1 47.9 07:03 6.6 2.6 48.8 07:04 6.5 2.3 48.8 07:05 6.5 2.2 49.9 07:06 6.5 2.2 50.7 07:07 6.4 2.1 50.7 07:08 6.3 2 51.4 07:09 6.3 2 51.9 07:10 6.3 2 51.9 07:11 6.3 2 52.3 07:12 6.3 2 52.9 07:13 6.3 2 53.4 07:14 6.3 2 53.4 07:15 6.3 2 54 07:16 6.3 2 54.7 07:17 6.2 2 54.7 07:18 6.2 2 55.2 07:19 6.1 2 55.6 07:20 6.1 2 55.6 07:21 6 2 56.1
What do you think? Are these better? Not sure what I'm looking for to be honest :-)
The idea was to check if the pump was set too high, which it may well have been. Compare your last figures and you will see that the GT10/11 range was smaller.As Manuel says in Fawlty Towers: " I Know Nothing"0 -
Have you blocked additional heat in 5.5, I'm not certain but I think the compressor only goes to something like 57C.beardymarrow wrote: »Now all I need to do is to figure out why my hot water peak isn't cutting in :think:. I think I'm going to change it to daily and then turn off the DHW blocking overnight to see what happens. If that works, I'll re-instate the block, and then if that doesn't work I'll set it to weekly and re-instate the block (except on the day it's supposed to do the peak). I know the block shouldn't matter as it should cut in next time there's a DHW heat cycle, but I'm not getting the hot water peak at all.0 -
Additional heat function will still operate in extra DHW and DHW peak, even if disabled in 5.5.Have you blocked additional heat in 5.5, I'm not certain but I think the compressor only goes to something like 57C.
You guys are certainly getting to know the system now :T:TAs Manuel says in Fawlty Towers: " I Know Nothing"0 -
Beardy: Did you have any luck with the DHW peak cycle operating?
Patrol: How is yours operating now and is there still a problem with the pressure valve?As Manuel says in Fawlty Towers: " I Know Nothing"0 -
I checked the valve, it opens with 1/4 turn. First couple of times it chucked out very brown water so seems to have remnants from a few years back. Just tried it twice now and it is running clear but will need to check dripping after a DHW cycle.
Figures are 14034 & 903. 5 hours heat pump, no additional heat since new 3 way valve but need to check a pasteurisation cycle.
Calcs. 5 hours DHW is about 8.5KW. At 9.2p/unit that is under 80p for about 3.5 days so 25p a day. The standing charge is more than that at 40p a day as I had selected a tariff to suit 8000-10000kw/pa which has been my annual use since 2007.
If the pressure valve is sorted my next job is to wait until November when heating requirements become more significant. Oh, and look at another electricity tariff when mine runs out in August.0 -
Oh, and I found these.
Ground loop manifold. Now enclosed in an inspection chamber into which I have placed about 50cm of polystyrene sheets to cover them. You both appear to have yours in more easily accessible areas.
Ground loop (2nd trench can be seen to the right). I tidied it up a bit as we backfilled. If the pipes looks unprofessional bear in mind it was all my own work and this was the first one - second one was done about 3 times quicker and neater too.
Making good. Looks neat here but the soil compacted and it was noticable for 2-3 years as a result.
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Beardy: Did you have any luck with the DHW peak cycle operating?
Patrol: How is yours operating now and is there still a problem with the pressure valve?
Sorry about the delay on reporting back. I've got the DHW peak set to Daily and it came on on Sunday morning when I'd got the DHW block switched off (Menu 4.3) for that day.
Compressor kicked in at 01:00 for 18Mins until GT9 hit 53c (normal DHW switch off temp), then the compressor switched off and the 6kW add. heat kicked in for 52Mins until GT3 hit 65c (it seems to use GT3 for the DHW peak temp switch off, but GT9 for the normal DHW switch off).
The rest of the week so far the DHW block was still on, and the DHW peak didn't kick in. So, long story short, the DHW peak doesn't kick in on mine if the DHW block is on for that night. That's cool. I just need to change the block to be off on the day I want the DHW peak to run.
FYI - Since DHW recirc valve closed, approx 6Hrs between DHW heating cycles. Before it was about 3Hrs. :T
FYI2 - 17kWH day yesterday (total consumption for the whole house). Whooo hoooo! My personal best.0 -
<snip>
Calcs. 5 hours DHW is about 8.5KW. At 9.2p/unit that is under 80p for about 3.5 days so 25p a day. The standing charge is more than that at 40p a day as I had selected a tariff to suit 8000-10000kw/pa which has been my annual use since 2007.
<snip>.
I think 5Hrs DHW is more than 8.5kWH. My compressor draws 2.7kW for DHW (mine's an E9 so yours might be less if it's a smaller model), 180W for the ground loop pump (P3) and 100W for the Heat Fluid Pump (P2), so that's 3kW when producing DHW (15kWh for 5Hrs).0 -
Your figures look loads better so here's to a cheap summer! Are you going to keep the recirculation off.
Mine is 1.4kw heating / 1.7kw DHW and I didn't include the pumps which would increase it to about 2kw. However, it should have been 3 hours operation not 5 and was unchanged when I got home tonight so operating for peanuts at present.
My smartpower gadget reckons 132 units total household use over the last 7 days and 12.73 in 22.5 hours today. Performance after valve replacement is exceeding my expectations.
Still not seen a DHW cycle to check the pressure valve. Been out a fair amount but also showing how much less frequently the water is heated.0
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