Heat Pumps - post here.

Thespoofer

Looking for opinions guys if possible.

Both heat pumps, which do ye think would be ' better'.

My house, old , I renovated, alot of insulation, external/internal, new windows/doors, plumbing/electrics etc etc.

At present stove with back boiler for Rads/DHW or immersion. Was going to install oil , we know better now of course.

Had the place assessed & air tightness test done. Doesn't qualify for heat pump grant but air tester did say its up to fairly good standards ( 2019 ) for an originally old place.

Down to x2 options, ( in my opinion ),

A2A heating & cooling HP or exhaust to air & water HP.

I like the idea of the heating and cooling, are they 'efficient' ?, as in does the unit produce multiples khw output for every 1khw in ?

Was working on a site recently and saw the exhaust in operation. Lovely and cosy but plumber reckons they could be expensive and it's like an 'immersion' always on. Not sure about this comment.

I'll be hoping to get solar installed eventually ( with water diverter ).

Apologies for long post. Any experience in the above would be appreciated.

Thanks

newhouse87

Well insulation wasn't it, used 33kwh overnight on heat pump. something seriously amiss with rooms, sitting room stat calling this morning for heat, no evidence of heat under while main bathroom v hot. Im going to have get commissioning fella out to see as plumber hasnt a clue.

Nelbert

https://www.boards.ie/discussion/comment/120204042#Comment_120204042

You'll need to remind me.. are you the chap with stats and zones messed up? I.e. kitchen stat heats bathroom?

You'll use an awful lot of energy if a room calling for heat is actually opening an actuator for a different room (it will just keep the call for heat and never stop).....

newhouse87

https://www.boards.ie/discussion/comment/120204430#Comment_120204430

Yeah think they are messed up but not sure. Im still thinking my heat pump isnt efficient enough even it rooms its heating. Like how long should a room take to heat back up to 21 once it falls to 20. Can it take hours? Ill post pic my manifold shortly when i get it. How much kwh should a heat pump use in an hour? 33kwh from 10pm to 7am seems mental.

Nelbert

https://www.boards.ie/discussion/comment/120204463#Comment_120204463

Mine uses 4-5 kW when it's getting the hot water back to 50 (from 38) for about 40 mins.

When answering a call for heat about 3kw until flow is to temp and then around 1.8kw maintaining flow temp and circulating.

Is the 33 just heat pump or whole house?

You need to sort the manifold and actuators out. If your kitchen is cold and calling for heat it will just keep calling (keeping pump running) if the heat is going elsewhere.

I used 10kWh on heat to top up bedrooms and heat the kitchen and hall floors (about 55m²) since 3am. That took kitchen from 19.3 to 21.5 with a lot of retained heat - floor still warm and kitchen now over 25⁰ due to solar gain so I'm nearly at no heat season albeit this morning was particularly cold.

newhouse87

https://www.boards.ie/discussion/comment/120204610#Comment_120204610

20230205_124914.jpg

Thats the manifold. Often notice that when kitchen calls for heat all actuators on left open aswell as 2 on main block but when other rooms call for heat the actuators on left dont open. 33 is just for heat pump. Whats best way to figure out if sitting room is actually being heated. Main bathroom very hot this morning from sitting room stat calling for heat. All help much appreciated.

Nelbert

Ok so the good news.... You've the same wiring Centre as me.....

The fused spur above should (I assume cut it off) - the light will go out.

What you need to do first.... Make each room call for heat individually and see which zone number light comes on on the wiring Centre and make a note of:

1. The room the stat is in

2. The zone number on the wiring Centre

3. The room that actually gets heat.

Once you have all of that you can turn off the power to the wiring Centre and take the front cover off (2 screws on far left and right in the middle height wise).

Then add to your info above and that zone 1 is actuator 1,2 and 3 (I'd number from left to right). Zone 2 is actuator 4.... Etc. By following the cable from the wiring Centre to the actuator.

You'll then be able to trace the stat to the wiring Centre (zone lights) and the zones to the actuators. Where 1 and 3 don't match should be easily fixed by swapping actuators around to the right manifold port and / or rewiring to the right zone.

Page 10/11 of the below will help

https://www.underfloorheatingsystems.co.uk/wp-content/uploads/2017/03/HeatmiserUH8_Manual_21062016.pdf

Make sure the power to the wiring Centre is completely off if you want to rewire actuators or stats though or it'll be more than a warm floor that wakes you up.

newhouse87

https://www.boards.ie/discussion/comment/120204733#Comment_120204733

Thanks man, will aim to do that on my day off. Finding it hard to determine if sitting room is getting any heat. Timber floor never feels warm and stat temp doesnt go up after couple hours i think. Stuipd question but are the actuators on the left exact same purpose as main block. They only ever open when kitchen calls for stat.

Nelbert

https://www.boards.ie/discussion/comment/120204781#Comment_120204781

I was lucky in that my misalignment was on rads which are quick to heat up (so you can figure it out quick) and it was a quick swap of actuators that sorted it.

I would assume so but the junction box behind it throws me a bit but that could be just the cables on the actuator weren't long enough.

Not sure about yours but my actuators had a red piece emerge at the top when they opened too so you may potentially avoid taking the wiring Centre cover off if you can easily identify which stat opens which actuator.

newhouse87

https://www.boards.ie/discussion/comment/120204836#Comment_120204836

Yeah mine have red bit visible when they are opened too so no need to open wiring centre so?

Nelbert

https://www.boards.ie/discussion/comment/120204848#Comment_120204848

Hopefully not. Once you can trace everything to what actuator reacts to what zone and which stat lights up which zone.

Only reason to open it would be if you've something wrong and it's not a straight swap.... I.e. zone 2 has 3 actuators and zone 3 has 2 and you need to swap them.

graememk

Ah yeah I remember you now.

Yeah I'd do all what Nelbert says. Try and get all your knowns, known!

What stat turns on what actuator.

If say the living room is calling for heat.. all the time, the heat pump will be running (and sounds like overheating the bathroom!)

The heat pump could hitting a max temperature, shutting off and reducing efficiency etc. Sounds like your not getting heat into your living room at all. The size of the heatpump it very unlikely to be the reason.

JoannaHiace

I'm looking to get a heat pump for a semi-D with a family of 4 living in it. Assume that nobody is at home during the day. Assume its B rated BER.

What's does the curve of typical energy usage look like during any given day?

Is it drawing electricity a little bit all the time.. or are there pronounced peaks?

If anyone has some perspectives on this I'd be most grateful.

Thank you!

Tar.Aldarion

Anyone have insight into good settings for these? I have a night rate so set the tank to 55 during the day and 60 at night so that it is on more at night than day, what numbers do people usually set?

Do you guys set the stats to the same 24/7 or have different temps at different times?

What kwh would your pump use per day?

Nelbert

https://www.boards.ie/discussion/comment/120299835#Comment_120299835

The answer is it depends.

I set back all temps around 11pm each night then put them back up around 4am so that the UFH downstairs heats the floor and there's a warmth in the house when we get up and for the rest of the day.

Motivation was partially based on being on a day / night meter and also suited our living patterns as we've south facing windows in main living space so get some heat gain during the day.

Today including a reheat of the hot water tank used just under 10kWh but all before 8am day rate start.

the_amazing_raisin

https://www.boards.ie/discussion/comment/120301070#Comment_120301070

Unfortunately I don't have per day kWh figures, but recently I tried setting my heat pump to a higher setpoint downstairs at night during the night rate tariffs

Tbh, I'm not 100% convinced it had as big an effect as I was hoping, you can see from the meter readings below that I shifted some consumption over to night rate but only decreased day rate by 40kWh

Overall energy consumption went up Vs 2022 but I think that's mostly from my wife charging her EV more than last year

So I'm still not sure there's a good way to do it via the temperature settings

There's a thread about using a Daikin heat pump as a diverter where it'll ignore the setpoint and just heat as much as it can. It's possible an approach like this would be useful here

poker--addict

I have a very hungry geothermal pump. Easily 40KW per day, abit more in freezing weather.

I have also tried to load shift to night. It has helped, but it feels like damage limitation for what I suspect was a bad setup. As in effect we end up running it like a boiler on a timer.

I turn it down 8am to 11pm (day rate). Then normal setting 11-4 or 5, then high for 2-3 hours before day rate kicks in so there is some heat produced for a few hours into the day. I have played with running for an hour mid/day on normal temp too in order to try keep water temps more consistent/smaller range, but tbh don't think it changed much, bar maybe on very cold days it topped things up a little for the evening.

This did shift a large chunk of usage into night rate but comfort suffers somewhat and doubt it does the pump any favours.

JoannaHiace

Thanks that's really interesting. Sounds like heat pumps tend to be used a little, a lot. Unlike gas, where we have it on for an hour in the morning and 3 hours in the evening. That gives me a better idea of my strategy here...

1. So yeah, So perhaps I could take advantage of the night rate to build some warmth cheaply.
2. I was thinking of getting solar PV panels. We wouldn't use a huge amount of electricity during the day, but my thinking was that if the heat pump is drawing a fairly steady current (which it sounds like it does for most people) then the generated electricity could be used by the heat pump (instead of selling it back to the grid, or getting a battery).

Our roof is South-East / North West, which I don't think is quite ideal for this scenario... but I would be tempted to split the panels 50/50 between the two sides so that we would get some electricity in the evenings (when we would need it)

the_amazing_raisin

https://www.boards.ie/discussion/comment/120303828#Comment_120303828

If you're thinking about getting solar then I would definitely recommend reading this thread

https://www.boards.ie/discussion/2058104393/daikin-altherma-3-and-solis-inverter

Calahonda52

https://www.boards.ie/discussion/comment/120303828#Comment_120303828

A couple of basic facts need to revisited

1: Max PV generated in summer months when minimum energy demand.

2: Max PV out put during daytime, when energy demand can be at it lowest.

3: Rad based Heat pump systems mitigate against the best use of night rate.

4: UFH based heat pump systems facilitate the maximum use of night rate.

5: Heat pumps don't like cycling, shortens life of compressor and kills the COP

6: Max COP from lowest delta T.

7: Rule of Thumb, aka TotT, design will not lead to a good HP system.

8: HPs like to run for long periods.

So, if looking at a PV array, we need some sort of an energy store.

The article below, which is worth reading in some detail, points away from the usual energy store with a heat pump which is a buffer tank.

{Am not convinced iff the system was UFH but most retros are with rads]

So a battery storage system would allow for intra day energy storage but not intra seasonal energy storage.

It would also allow for top up on night rate.

However, the size required may be significant, depending on load:

https://renewableheatinghub.co.uk/how-to-correctly-install-heat-pumps-so-that-they-work-properly-and-efficiently

THE ALM

So much information out there when trying to decide on installing a heat pump with a lot of it conflicting.

Been doing a lot of research into this with a view to replacing our aging oil boiler. The article Calahonda52 linked is a great read and demonstrates that they work well when installed and set up properly, HeatGeek are also very informative with great videos.

We have put a lot of work into upgrades in our house and have spent a lot of time making things as airtight as possible, some of which are very cheap and easy fixes. Has been a lot of expanding foam and a lot of time and effort removing 35 downlights, filling and sanding but made a huge difference.

Some effort is required but unless we sort out these problems, a lot of them small, then there is no point in even looking at a heat pump.

Just had a an airtightness test carried out yesterday with the tester being impressed with the level of airtightness we have achieved for a 17 year old house (note - those attic stairs are right leaky even with a rubber seal round them) and beating some modern builds that he is doing. Waiting on the official cert but it is looking good. Speaking to the tester he has great stories and not so great about heat pump installations but reckons we are fairly well set up.

Have also turned the boiler stat to it lowest and have been monitoring the flow and return temps to see how we cope, next week will be a tester!!! I'll run the boiler more like a heat pump and see how long it is firing for compared to the usual blast in the morning and evening.

Job for the afternoon now is sealing the attic stairs better and we have a vaulted ceiling in the kitchen with the top section above ceiling level being a single block internal wall which has the cold attic on the other side so a big cold bridge which reads several °C lower than the lower section of wall. Again, a small couple of jobs but will eek out another bit of thermal effeciency.

Dozz

@THE ALM can I ask how you are monitoring the flow and return temperatures?

THE ALM

https://www.boards.ie/discussion/comment/120314308#Comment_120314308

@Dozz I use a Shelly 1PM with the add-on with a couple of temp sensors which are attached to the flow and return of the boiler. The boiler is powered through the Shelly so I can monitor when it fires.

Calahonda52

https://www.boards.ie/discussion/comment/120314404#Comment_120314404

Looked at this rig on line here

https://www.ebay.ie/itm/203658015363?var=0&norover=1&mkevt=1&mkrid=5282-166454-587998-0&mkcid=2&mkscid=101&itemid=v1%7C203658015363%7C0&targetid=1904072576865&device=c&mktype=pla&googleloc=9040155&poi=&campaignid=19113887749&mkgroupid=147914594830&rlsatarget=pla-1904072576865&abcId=&merchantid=697721261&gclid=CjwKCAiAmJGgBhAZEiwA1JZolum-cO4J9jQedyjsjFaSeFjAWntngO8RZkDCv3TjzgaGexwci4CFFxoCj28QAvD_BwE\

what else do yo need?

Any chance of a simple schematic?

Thanks😀

THE ALM

https://www.boards.ie/discussion/comment/120316143#Comment_120316143

If you get a Shelly plus device and then the Shelly plus add-on with the temp sensors (https://www.shelly.cloud/en/products/shop/shelly-plus-add-on/shelly-plus-add-on-2x-ds18b20) If you don't require power monitoring then the Shelly I Plus will do.

The add-on simply pushes on to the plus device and the temp sensors are simply wired to the add-on. The add-on can take various types of sensors.

Better value buying direct from Shelly and they often have special offers.

I can take a picture and post a simple schematic but is very straight forward and the schematics are on the Shelly knowledgebase.

As with anything electrical take all necessary precautions. As stated I have the Shelly 1PM powering the boiler so feeding 240v.

graememk

https://www.boards.ie/discussion/comment/120316217#Comment_120316217

If you could hook up a flow meter, you could work out the kwh heat required for your house

THE ALM

https://www.boards.ie/discussion/comment/120316441#Comment_120316441

Yeah, have the heat loss worked out so just seeing how running the lower temp on the boiler feels in real world terms.

I'll need to sit down and put all the figures together and see how it all looks and then look at getting a good installer.

gandalfio

So I've read that the external weather thermostat needs to be on a north facing wall or gable.

Our heat pump is on a south facing wall and was in sunlight for a lot of today.

For example, today the outdoor temperature reading on our panel in the hot press was 10 degrees. Even though it was 0 degress outside.

Is this something we need to address? What impact does the above have on the effeciency of the heating system?

graememk

https://www.boards.ie/discussion/comment/120326337#Comment_120326337

It may mean that the heatpump will run at a lower temperature depending on what the weather compensation is set at, thus not putting enough heat into the house. If the house is warm enough, dont worry and let it work away.

JoannaHiace

https://www.boards.ie/discussion/comment/120309772#Comment_120309772

This was a very interesting article - thank you.

My understanding from that article is that heat pumps like to be on LOW and for LONG periods of time.

To achieve this, the house needs to be well insulated... so that A: a low setting is sufficient to heat it and B: you have a steady comfortable ambient temperature rather than a hot and cold rollercoaster (e.g. pressing boost on your gas boiler).

So... most likely your heat pump is going to be on at night time of course, which is good because you're getting the benefit of night rates.

AND... the heat pump is likely to be on during the day time - so if you have solar PV that happens to be producing energy you will get the benefit from that.

But I think the moral of the story here is that you don't want a situation where the heat pump is turning on and off based on when the sun is shining.

However, I wonder about the scenario where your PV is simply heating an immersion coil rather than the actual heat pump itself? I had thought that this might be an interesting way of doing it. But based on this article I'm not so sure. Because if you do generate sufficient energy to heat the water significantly then there's no point in having your heat pump on... so it'll turn off... which isn't what you want to do. You're back to this rollercoaster situation again.

So in summary... make sure the house is well insulated so that the heat pump can be on low for long periods of time, and if some of the energy is provided by solar... well that's nice.

Is that fair?