Heat Pumps - post here.

johndoe11

https://www.boards.ie/discussion/comment/121590698#Comment_121590698

No it's not, I very happy with the setup now. It hasn't been above 3 since Saturday morning. I have noticed, given how cold it has been for the last 3 days, I find the indoor temperature is drifting down a bit from 21 to around 20 this morning. To keep it at 21, I may have to raise the curve a bit higher. The defrost cycles are a killer at these temps, runs about every 70 mins when below zero.

graememk

It should need to defrost less if the temperatures get lower. Around 0-4 is nearly the worst for frosting

dominatinMC

https://www.boards.ie/discussion/comment/121590353#Comment_121590353

That's incredible usage in this weather. Are you runing fixed flow (if so, can I ask what temperature) or weather compensating? If weather compensating, I'm assuming you've calibrated your own curve?

johndoe11

https://www.boards.ie/discussion/comment/121590809#Comment_121590809

Didn't realise that. Maybe there is subtle differences in the intervals on mine, but it seems fairly regular when you look at the compressor output.

HotSwap

https://www.boards.ie/discussion/comment/121591002#Comment_121591002

Also what’s the COP?

graememk

https://www.boards.ie/discussion/comment/121591233#Comment_121591233

There's less moisture in the air, the colder it gets, but it would need to be like below 5 or more

Scoopsire

https://www.boards.ie/discussion/comment/121591002#Comment_121591002

Great going! any idea what the build up of the house is as, ie u values of walls, floors, roof, etc?

DC999

https://www.boards.ie/discussion/comment/121589626#Comment_121589626

I’m like you seeing how heatpump-ready our leaky house is. But you won’t need a 50C flow temp (like you have now on your oil boiler) when the system is running 24x7 (ok, you’ll have a lower setback temp for nighttime). Our sitting room went from 21C last night to 13C this morning when the room wasn’t heated overnight. That’s a massive drop but expected with no insulation and old windows in that space. But if I had a heatpump with a setback it would never get that low. And you'll also have thermal mass in any thick walls too so will help retain the heat.

Looking at the delta conversion, at 35C you get 65% the heat output of a 50C flow temp. So if your rads don’t need to run 1/3 of the time now, then you could (in theory) run the heatpump at 35C flowtemp. As you say, wind sucks the heat from buildings of course. Graeme sent one of these but from the BER calculator side I think (or DEAP calculator I think). If I’m reading it correctly it shows a 35C flow temp is .657 of a 50C flow temp. 

newhouse87

https://www.boards.ie/discussion/comment/121590353#Comment_121590353

Is that 19deg on room stats from chart? Big difference in this weather having 21/22 versus 19 I would think. Your usage is very good for this weather.

HotSwap

https://www.boards.ie/discussion/comment/121592658#Comment_121592658

I’m already running the oil like a heatpump to see what it’s like.

I have a grant vortex 15-26 kw unit. Which is currently configured as 26kwh output. It’s possible to change the nozzle which makes it a 15kw max output; which would make it equivalent to a 4-5kw heatpump. I’m tempted to try this; it would make the system run even more like a heatpump; less cycling; and probably even more efficient if the 15kw is enough.

staples7

https://www.boards.ie/discussion/comment/121590518#Comment_121590518

https://www.boards.ie/discussion/comment/121590698#Comment_121590698

7.4 kWh Solar installed before Christmas but won't make much difference to my heat pump setup unless I went down the big battery route.

HP in 7 years, I did do a good bit of tinkering at the beginning, basically a timer setup ie if its not reached X temperature call for.

However in the interests of honesty what I will say is that the below screenshot timer setup would need to be adjusted in the freezing weather especially when there's no solar gain in the day. I haven't done this this week so the temp tonight sits at 19', probably a bit lower than id like but not uncomfortable. Would want it to sit at 20+

Set to 16' at 8am to prevent limit heatpump to night rate.

I haven't adjusted the flow rate or anything else in the background either, you'd probably have to show me where to check even!

championc

It really is worth doing. It's the true way of seeing if the rads are ok or undersized.

I'd doing similar with a gas combi which unfortunately is non-modulating. Although I really have no intention of running a unit 24 x 7. I plan to run shorter and hotter, and take the hit on the COP at the expense of the unneeded hours.

Anyone else doing or tried similar ?

And anyone running a Vaillant AroTHERM here in Ireland ?

newhouse87

Yeah tbh if my house was 19deg the usage would be good bit lower, kitchen at22 this evening and other areas 20/21. Im running fixed flow 31deg now at 9am-10pm and house staying up to 19/20 overnight so morning time still fine. Approx 26-28kwh usage including dhw. Ran sunday24/7 and it was colder and usage near38-40kwh.

Dozz

https://www.boards.ie/discussion/comment/121593866#Comment_121593866

How do you configure it to run as 26kw output?

I'm currently running my grant boiler at its lowest flow temp (55 degrees I was told) to see how the house copes and so far so good.

poker--addict

Those of you with ground pumps,

what is your inbound and outbound temperature on the ground loop?

I might have found my problem....

HotSwap

https://www.boards.ie/discussion/comment/121593968#Comment_121593968

Is that just coming on for an hour between 1-2 am, then another hour between 5-6 am, etc…

HotSwap

https://www.boards.ie/discussion/comment/121594252#Comment_121594252

Mine came configured for 21 out of the box. Not 26 that I mentioned (my mistake) To downrate it you need to replace the burner nozzle (https://mybuildingsupplies.ie/shop/plumbing-heating/oil-boiler-spares/burner-nozzles-for-oil-boilers/)

according to these guidelines (this is my boiler):

So my boiler can be configured to either 21, 18 or 15.

the stat just controls when the burner stops and starts firing; mine will burn outputting. So mine will fire; outputting 21kw of energy into the water until it reaches 50C; at which point the burner will cut out; the water will keep pumping around the rads, and eventually when it drops below 50C the burner will fire again.

if I changed it to only output 15kw of energy; it will fire; and more slowly bring the temp of the water towards 50C; but it’s only burning 1.28L of oil vs 1.78L per hour of operation.

it’s definitely an experiment that I want to try.

the range on the stat is defo 50-75

staples7

https://www.boards.ie/discussion/comment/121595012#Comment_121595012

No it stays on until it’s is 1’ clear of whatever it was set to. So potentially in my screenshot it would stay on from 1am to 8am if the temp was not 20’

Dozz

@HotSwap thanks for that. Very helpful

PCDub

https://www.boards.ie/discussion/comment/121595069#Comment_121595069

Have the same boiler and looked into changing the nozzle to reduce oil use but replies i got was its not just as simple as swapping the nozzle.

Oil pressure, air intake and combustion chamber may need adjustment. Ideally would get an oil boiler service engineer with a meter to make sure all is ok after changing nozzle.

HotSwap

https://www.boards.ie/discussion/comment/121595860#Comment_121595860

Yeah; it’s prob not one I would attempt myself. But; it’s fully documented how to do it so it’s not totally impossible.

Apparently there is a nozzle shortage on at the moment too; so certain types can be hard to get hold of.

KCross

https://www.boards.ie/discussion/comment/121594954#Comment_121594954

I have a Nibe HP with horizontal collector.

1°C right now outside and the "Brine in" is about 6°C and the system will modulate the flow rate to have a delta of about ~5°C between in/out so "Brine out" is about 1°C

This is really where a ground source HP shows its worth.... the system is getting 6°C from the ground (while its below freezing in the air) and not suffering from frost/defrost cycles.

I might have found my problem....

What have you found?

micks_address

This might be a daft question so apologies in advance. If you wanted to see how you'd get on with a heat pump, having an existing gas boiler.. could you test running the gas boiler at a lower flow temp, say 30 degrees and see how comfortable the house would be?

I'm curious how lower temp rads on for longer periods would heat the house.

graememk

https://www.boards.ie/discussion/comment/121597017#Comment_121597017

Biggest struggle would be getting a boiler to modulate low enough to do a proper test. (To 30..)

It may cause the boiler to cycle a bit more, possibly good for a test but not full time use.

Start dropping it until people complain 😂

Urban plumbers just uploaded a video where he is running is gas boiler at 29

https://youtu.be/tPQpxiBT8no?si=9oFALLranumbz0tq

micks_address

https://www.boards.ie/discussion/comment/121597194#Comment_121597194

Yeah that's what got me thinking about it

graememk

https://www.boards.ie/discussion/comment/121597230#Comment_121597230

compact-radiators-delta-t50 (1).pdf

If you measure your radiators you could estimate the power from them

Delta 50 is the difference between the room temperature and radiator temperature.

If your flow was down at 30, you'd only have a delta of 10, for a 20c room.

Radiator would put out a tenth of the "reference" output

DC999

https://www.boards.ie/discussion/comment/121597194#Comment_121597194

What’s the impact of cycling a gas boiler? The fella who did the yearly service also suggested turning it as low as possible.

I’ve it set to the lowest it will run. Heats for 30 seconds and then pumps for 60 seconds. I’ve had it on that for 1 year but only run the heating 3- hours a day (use electric rads in between). 15+ year old non-condensing boiler so won’t be efficient in terms of heat conversion. House temp swings too much if it's turned up more.

poker--addict

I got some cheap amazon thermometers, they are now attached to the pipe with some insulation or insulating tape holding them tight to pipe (pump doesn't have a read out)

What I have found is both in and out appear to be cold! -1, and - 3.5

Like all things heat pump it doesn't necessary give a straight indicator of what is going on, I can think of a few

1) is the horizontal collector too shallow; deep cold snap here until yesterday, did the ground freeze that hard and is lagging warming up.

2) is the collector too small; and the energy is gone from the ground half way through the season- this seems the obvious answer BUT in this case I would notice efficiency difference between 1st of october and 1st of March, and I don't really, it's crap all the time

3) fluid is being pumped too fast and has been in demand a lot the past week, so isn't get a chance to warm up

so now I am waiting for rain to see if that makes a big difference in the loop, which would imply it's too shallow or the ground is being drained of energy (too short).

in some respects the loop being a problem would mean I go Air2air or air2water with no regrets, but I'd rather not waste a good ground loop if it's ok.

poker--addict

In addition I have put thermometers on the buffer in, and it's firmed up my view that the buffer makes zero sense. When the zones close the flow reduces and water goes back to pump not to buffer, tbh I'm even more clueless now what possible correct logic would exist for the buffer

graememk

https://www.boards.ie/discussion/comment/121599230#Comment_121599230

Get a picture of it for us,

As its sounds its a volumiser not a buffer (Still a tank, I know)

https://www.boards.ie/discussion/comment/121599221#Comment_121599221

Its not been that cold outside, Was much colder in Dec.. Could try digging a hole in the garden to see how much its frozen?

Interesting to see the comparison of the flow and return of the ground loop, the difference is very small.

What you said about flowing too fast around the loop, doesnt really matter, If you half the flow, and only double the temperature difference, the amount of power you are extracting is the same

P(kW)=flow rate(l/s) * temp Diff in C * 4.18 if water or 3.14 if glycol

If you are getting 10 KW of heat into your house, your pulling that amount of heat from the ground [possibly a bit less as it can grab heat from the compressor etc]

you have a delta of 2.5 whereas Kcross has a delta of 5. For every litre of fluid he gets twice the heat out of it vs what you are getting