Heat Pumps - post here.

You are logging the outdoor unit as this is where the vast majority of the energy is used. TBH I think the only thing the indoor unit/tank uses is when it goes into the legionalla cycle once a week it uses the emersion for about an hour, mine is 2kW for about an hour one a week.

Otherwise a 50 amp CT is ok as it will only be drawing at MAX 4-5 kW

I agree with everything except the heat pumps. They're a bomb waiting to go off. Maintenance cost, running costs, and no grant to replace when it dies in ten years, like running an extra car. And the electricity they use is 80% generated from fossil fuels ffs. Just burn the gas in a small cheap efficient boiler in the home.

One of the biggest lies. Ten Kw of gas turns into 9.7 Kw of heat and HW consistently in your simple inexpensive long lasting and small gas boiler.

10Kw of gas burned in a gas turbine generator produces maybe 3kw of electricity, grid losses to your Heatpump and heat pump losses another 10-15% . You're left with maybe 2.6Kw into the compressor, with a Cop of three if its a warmish day, 2 and a bit on a cold one, so you get maybe 7.5kw out, maybe 6kw. This is low water temperature heat, very slow to warm a house, and unless you have a 12kw input heat pump, you won't have the level of output heat of even the smaller gas boilers to bring a typical Irish 80s house up to warmth quickly. Many people still only heat their homes in bursts, or a few rooms at a time. Heat pumps only work when your home is insulated to within an inch of its life, as in Scandinavia etc. Then its possible using a low kw input heat pump to gradually bring the entire home to a comfortable temperature and maintain it without going bankrupt. A 12kw heatpump costs €5 an hour to run at current daytime rates, and as much as €7/hr on some of the smart peak evening rates. Heatpumps require hugely insulated homes, and huge radiators or eye wateringly expensive UFH to even begin to make sense. Houses in Ireland are not insulated properly, and A rated new houses are an illusion, the rating gained by sleight of hand and statistics, while icy draughts whistle in your vents and down the back of you drywall.

And no-one seems to factor in the huge overhead of standing charges on electricity. I only pay for my CH oil. If its unused during the summer. It costs nothing. If I burn a litre, I get almost 10kw of HW from my condenser boiler for €1.

Like I said, if the house is suitable. Anyone recommending a HP in an 80's build should not be trusted.

Got the technical assessment done, and I know it's a long time since it changed, relatively, but when I finally get quotes in and get the work done which was going to precede the installation of a new pump - I find the SEAI no longer provide the heat pump grant for houses which have an existing pump. They changed it in January I think. A 6k kick in the nuts is not a nice thing to receive first thing on a Monday. Only paid for the technical assessment based on the SEAI information, which checking the wayback machine changed without warning earlier this year.

its ridiculous. Apparently some crowd in Kildare screwed up an estate with 100 pumps. Told the occupants after a year or so to apply for grant and the pumps were all pulled out and redone, rinsing the tax payer- regarded as a total abuse of the system by the organisation involved, and others in the industry are unimpressed. The result is SEAI slamming the door on genuine cases.

the big issue with no grant for replacement is grants drive prices up, so replacement candidates are not playing in a free market, and government should have at least a partial payment as a result. People will start sticking in gas boilers to replace heat pumps if they are being asked to pay 10-15k, up to 20 odd for larger systems.

It’s actually 6750 in total as you get a contribution for the technical assessment too😫

Research evidence in the UK suggest that COP of 3.5 is barely reached by super insulated almost passive homes, and well less than 3 for average homes. I smile when I see enthusiasts mentioning COP of 5. That's a nonsense figure, which would require the return flow to be virtually chilled before entering the condenser. Once homes feel cold people turn up the stat, causing the heatpump to churn away, adding extra heat to the flow almost exclusively from the energy of extra consumed electricity. Some heatpumps even have an immersion element for HW! Don't tell Des Bishop that.

Thoughts on the following heat pump for a 2000sqft bungalow - https://www.heatmerchants.ie/panasonic-aquarea-9kw-j-generation-high-performance-mono-bloc-unit-u27640

Underfloor heating, well insulated to a2 standard.

Yes, the system has been designed together if that makes sense. Just wanted to run it by the well informed here to see was there any red flags or horror stories with this unit!

I originally brought up heatpumps in this forum to alert readers that they are primarily powered by fossil fuels, at great infrastructure cost at either end of the chain. The other reason which should be self evident is the notion beloved of eco greens that it is somehow viable to operate a heat pump from domestic stored solar. You might easily consume 60 to 100kwh of gas or oil daily in the winter months, which would translate into 20 to 33 kwh of live/stored solar energy to a heatpump per day, IF a cop of 3 is achieved. For this you'll need probably €60,000 worth of solar plant, and 150m2 of panels. It's just not possible unless you have a very large garden, and a big wallet.

This is a more realistic assessment of COP than a single experimental tale. https://housingevidence.ac.uk/the-great-heat-pump-mystery-wheres-the-cop/#:~:text=values%20experienced%20in%20real%2Dworld,number%20%E2%80%93%20based%20on%20laboratory%20tests.

I agree that Heat pump discussion here is of no relevance to domestic solar. Solar is absent when heat pump demand is greatest, in the winter, at night. They're almost mutually exclusive.

Looking at buying a place with a very old gas system that will need to be ripped out. I'm looking at heat pumps to replace. I will get some solar panels in the near future but in the winter that's not going to work.

For the winter I'd rather use the nighttime rate, For 6 hours I get it cheap enough.

Would a heat pump be able to heat a tank over night which it could release during the day for the radiators? Even if I was able to use it for 8 hours would help.

I would also heat a different hot water tank during this time for showers/hot taps.

Also can they be connected to an air-con system for use in the summer?

What you're talking about is a buffer tank. You can get them with heat exchanger built in, or even an internal direct hot water cylinder, which seperates the sealed heating circuit water from the tap hot water. The only issue would be the maximum temperature output from a heat pump, it wouldn't make for thd highest volume of energy storage.

A fairly large 1500l tank would not store a huge deal of heat either. A 1500 litre tank heated from 20° to 55° stores 1500x35x4180 Joules, which is just under 61Kwh, so depending on what your home requires as input to maintain a comfortable temperature after the night rate, 61kwh should be good for three or more hours. It would be important to circulate it slowly from top to bottom, so that the maximum temperature fluid rises in the tank, replaced by the fully cooled return underneath, helping to to keep the hot flow temperature as high as possible for a steady heating performance until the heat pump kicks in.

Flow rate of 8.5 l/minute would move the entire tank through the system in three hours. Buffer tanks are 0 not commonly used here domestically, more likely in commercial plant where heat recovery from waste water and other sources is used to resupply HW and CH. Some big hotels also use the principle. Design and integration of such a tank requires a good bit of heating knowledge, but you could Google some domestic designs.

Stashing away 60kwh of hot water from a COP3 heatpump using 20kwh electricity input at night rate, of say 20c/kwh will cost €4, which is about €2 less than 60kwh ffrom an oil boiler.