How to correctly install heat pumps so that they work properly and efficiently

the_amazing_raisin · 13-01-2023 10:51PM

https://www.boards.ie/discussion/comment/120105354#Comment_120105354

100% agree, people would often say that gas is more cost effective that electric for cooking. It's easy to say that when the fuel is just really cheap, no reason to be efficient then

I suspect a lot of those folks with the huge fuel bills are not switching providers and are getting f!cked at the standard rates

I cannot understand people not doing that. I've known people who would drive across town for cheap petrol but won't spend 20 mins finding a cheaper energy tariff and switching

There's really a lot of disinformation around this. I remember a colleague of mine from India was complaining about the electricity bill in the house share he was in. I asked why they didn't switch provider and he said the landlord told them it would cost €300 to change

It's BS like that which keeps Electric Ireland and Bord Gais in business 🙄

graememk · 13-01-2023 10:56PM

Gas bills are every 2 months, like electric?

1000 euro is a shock bill.

I thought my last electric bill of 330ish was bad(before the gov credit)

Although short cycling on a heatpump can be very detrimental to efficiency. And with a buffer might mitagate it a bit, but then controlling it properly is the issue.

I can understand the heat geeks ethos not to zone on a condensing boiler or a heatpump to get the return as cold as possible.

.. have the number for a company that does the cavity insulation must get in contact with them.

ColemanY2K · 16-01-2023 04:15PM

https://www.boards.ie/discussion/comment/120105347#Comment_120105347

I'm continuously shaking my head when I see new builds with insulated plasterboard fixed to the inside face of a cavity wall. It shows a real ignorance towards the thermodynamic properties of a building.

Put whatever insulation you need into the cavity to achieve the necessary u value and just plaster with sand cement and a skim the inside face of the wall. That way you get a thermal store, a more comfortable room - as it won't heat up and cool down rapidly - and the air tightness task is simplified significantly.

Calahonda52 · 16-01-2023 04:19PM

Perhaps but chasing external walls for sockets etc and making the back of sockets airtight is a lot of work.

ColemanY2K · 16-01-2023 04:33PM

https://www.boards.ie/discussion/comment/120116113#Comment_120116113

chasing is not bad if you have the correct equipment and airtightness is easy and quick with the use of airtight paint.

Plasterboard on the other hand is notoriously difficult to make airtight as heat can escape from a multitude of places.

Calahonda52 · 16-01-2023 04:37PM

Valid points, Not arguing with you, just teasing out the issues :)

I sand and cement the wall even when using a pb service cavity.

I can't remember which way the dial is moved in a BER when all external walls are PB (light) vs block (heavy) when doing the thermal mass calc

DownByTheGarden · 16-01-2023 04:55PM

https://www.boards.ie/discussion/comment/120099596#Comment_120099596

That would be dripping with condensation though

ColemanY2K · 16-01-2023 04:59PM

https://www.boards.ie/discussion/comment/120116222#Comment_120116222

i'm afraid i can't claim to know the answer regarding the BER comment but to install pb on to cavity wall construction of a new build would negate the thermal store. This would in turn reduce the energy efficiency of the house, consequently putting more load on the heat pump in order for it to maintain the set temperature. in my head it defies logic when i think about it.

the_amazing_raisin · 16-01-2023 05:09PM

https://www.boards.ie/discussion/comment/120116113#Comment_120116113

I thought the idea then was to put the airtight layer on other side of the cavity to the plasterboard?

So the cross section from outside to inside of a timber frame would look a bit like this

Cladding (blocks or render) -> External cavity -> OSB with vapour barrier -> Structural timber with insulation in between -> Insulation panels -> Airtight barrier -> Services cavity with thin studs -> Plasterboard and plaster

the_amazing_raisin · 16-01-2023 05:19PM

https://www.boards.ie/discussion/comment/120116295#Comment_120116295

I think the theory behind timber frame houses is that they don't have much thermal mass to retain heat and instead use insulation to lower the heating demand

Hence the old saying that timber frame houses heat up quickly but also lose heat quickly compared to block houses

How well that theory works is a bit debatable, having less thermal mass gives you less storage but you also don't have to heat up that thermal mass in the first place

FWIW, I kinda agree that insulated plasterboard isn't the right approach. I'd almost be in favour of insulating the cladding instead and having the timber frame inside the insulated space. Probably better for the house's structure overall, keeping the frame relatively thermally stable

SD_DRACULA · 16-01-2023 05:46PM

I would agree with insulating on the outside but to do a full house is very silly money even with "grants"

The house already had interior insulation but it was that white crap they used in the 90s (before kingspan) stuck to plaster board (60mm or so) and then stuck to the wall with 2-4cm blobs of tile adhesive or something (max cowboys), no wood studs or anything (except in batrooms), which I'm sure for air circulation the empty space behind the pb helped but house was an igloo once the heating off and you could hear the wind.

Replaced it with kingspan and it made a big difference for sure.

Calahonda52 · 16-01-2023 08:01PM

The main improvement is due to getting rid of the dot and dab and closing that gap which was fed with air from wall vents as the wall vents were not fully sleeved all the way through.

I oversaw the remediation of 200 houses in Dublin back in the day just by using airtight tape to close the gap between the pb and the wall.

I did 2 houses, produced a little video and the residents took it on to help each other. Good community based project.

Tape was 23 a roll per house

..

aero board is 0.035

kingspans between 0.025 and 0.033

so not a massive difference

creedp · 19-01-2023 06:08PM

https://www.boards.ie/discussion/comment/120099842#Comment_120099842

I have a GSHP in a 2011 build house (A2 rated) all block build (internal & external walls) with concrete slabs on 1st floor Its a 12kw HP which is on all year but only heats the water from May to Nov. I have a meter attached and just checked it there and it has used 551 units in total over the last 36 days (av 15kw per day) all of which were used at night rate. I have ufh throughout and only have 2 stats, one on each floor. I think thermal mass is essential with HPs as you can heat the house overnight and it will pretty much last all day. I have no other heat source in house except for a log stove which I lit probably 5 evenings this winter to-date and that was only for the added comfort late in the evening. As for heat loss from hot cylinder, I have a 500l cylinder in the attic which has been kitted out as a large 'hot press'. I heat the tank every night to 50 deg c, which from memory only takes about 3 units of electricity (must check that again), and this lasts all day for all hot water use incl showers. The minor heat loss works great to keep the area 'aired' so I don't consider it to be heat lost.

So for me the HP has been a great success but the system was designed and installed as part of the new build by a guy who obviously knew what he was doing - unfortunately he's out of the game now so I woudnt even know where to start looking for someone to install a system. A couple of neighbours, who were very skeptical of HPs when I was installing given the high installation costs, are now considering retrospectively installing a HP given the low running costs of my set up but I have cautioned against simply drop kicking a HP into an older house with rads. It simply wont work as well and they will be hugely disappointed when the expected savings wont materialise.

Btw thats some battery capacity you have, I wouldnt mind drop kicking some of those into my ever degrading Leaf!!

DC999 · 19-01-2023 06:31PM

https://www.boards.ie/discussion/comment/120130428#Comment_120130428

Fair play to you for explaining your setup. 15kWh a day for heating a whole house is amazing when it’s this cold!! Summary - GSHP works a charm for you in a 2011 build house (A2 rated) with UFH concrete slabs on 1st floor. Which means new builds with UFH are very suitable for heat pumps with low running costs.

Old houses are a different beast. For us to get concrete slab UFH in an 80 year old small 2 up 2 down old Dublin council house would mean literally digging the solid floors out of the house to drop them down for UFH. That’s a mechanical digger inside the house I'd guess. Just not a runner unless getting work done where we’re leaving the house anyway, even ignoring the huge cost. I'd love an A rated house with a HP for comfort and low running costs. Need to buy that lotto ticket I think :)

the_amazing_raisin · 19-01-2023 06:50PM

Anyone want to learn how to install a heat pump?

https://courses.heatgeek.com/product/beis-funded-heat-pump-training/

Unfortunately I think you have to be a UK citizen to get it for the discounted price 😭

How to correctly install heat pumps so that they work properly and efficiently

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