Heat Pumps - post here.

We have an A3 house (1950s retrofit) and a combi boiler. We did the upgrades over a few years as oppposed to everything all at once so that was one consideration but we are delighted with the combi boiler - it makes so much sense for Ireland.

The maths for a heatpump just do not make sense for me, we spent under €500 on gas last year (admittedly will be more this year with the rate increases), so even lets say €1000 pa of a gas bill. Even if a heat pump were to save 100% of that (which it won't), we are talking 12-15 years minmum to recoup the after grant outlay, even will no other measures required

What thickness insulation are you putting in the floor and at the all perimeter?

I believe 50mm for floor (underfloor heating) all perimeter 25mm

That is 12k supplied or installed?

There was no site visit so remedial works were only assumed - but iirc included new rads throughout.

House is 110m2

No storage tank as we're coming from a combi boiler so that likely contributed to the cost alright.

No underfloor either, hence likely rad replacement

What would it be if we went with those #s, 325mm floor, all perimeter 75mm? Again, from my original post I've got two floors: 120m2 and 100m2, total 220m2 top spec insulation for completely new build.

I'm just trying to run a sanity check on the builder's proposal for a 16kW Samsung Gen 6 unit, which I think too high (maybe 8kW?). Thanks.

Thanks. If I look at a calculator like https://ecoplus.ie/heat-pump-size-calculator/ and put in a generous 220m2 for house area, HLI of 1.5 (also generous, it’s well insulated) and the temps as given (-3/20) I get a 7.6kW result/requirement. Maybe 16KW is overkill for my build? This site also mentions: “What happens if a heat pump is oversized?

An oversized heat pump will cycle frequently. This increases both energy consumption and wear and tear. Cycling can be reduced somewhat with a large buffer tank. Variable-speed heat pumps also minimize the cycling problem. But even then, the heat pump will run very frequently at part-load, reducing efficiency.”

And maybe going down some KW is supported elsewhere++ (e.g. https://www.imsheatpumps.co.uk/blog/what-size-heat-pump-do-i-need-for-my-house/ ), where a well-insulated 4 BR house needs c8KW (I’d note also an 8 only has 1 fan (and smaller footprint) versus the 16’s 2 fans, so noise may be lower).

I just saw your reply now. I must have missed the notification. Can I ask who you got these quotes off. I'm getting €1000-1200+ quotes (for those that will actually quote)

what part of the country are you in?

I have also found it hard to locate people. One issue seems to be many pumps installed involved a sparks and a plumber. Getting one around and not both may mean knowledge gaps. I eventually found a plumber who used to work with them and does the odd one. He is very knowledgeable, however I am out of his way.

Another issue is the pump is only half the battle of the issue is to do with efficiency- the wider setup can be a big part of any problem; thermostat setup, number of zones, UfH- what level is it at, properly insulated? Type of manifolds, circ pumps, are water circuits balanced. There are lots of variables, some may be unknown if original plans or installer aren't around.

There are many companies who seem to work with a lot of them but are also in the business of selling them. One told me I needed a new one without even looking at mine- he might be right but he seemed quick to diagnose an issue over the phone that two others half scratched their heads at while stood beside it.

I can only assume things will be easier to fix in 10-15 years, pumps hitting 15-20 years now should still work fine but they were earlier models and even finding a manual online can be tricky. As per the post above sometimes been finding out the name of the brand let alone the model is hard.

Unlike solar panels, this is one purchase where it is worth paying a premium for a large company with longevity, or someone very well known for their work with pumps.

It’ll depend on what has broken. Sometimes the part can be repaired/ replaced and the unit recharged with gas.

if you look on the Daikin ireland site there are a few options there for registered people. I use a guy who used to work for a company in athboy and find him good.

This is who we used, we're just south of ferns

• ANNA CODD PLANNING AND DESIGN BER ASSESSOR • Wexford • (tuugo.info)