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

Calahonda52

One view of the world in this space from a UK perspective where the use of buffer tanks seems more prevalent.

This article sets out the case for why buffer tanks deliver poor outcomes by way of lower COPs

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

graememk

Heat geeks have been saying that for a long time too. It does tie in with the no zoning ethos too, always allowing the heat pump to run at best efficiency

it makes sense, heat a buffer and that heats house vs using the heat directly.

SD_DRACULA

Interesting read, I was contemplating a HP but I think that 99% of installers don't have a clue how to calculate the size of the pump based on the property specifics and they couldn't care less about your bills if they got it wrong and your pump ends up working overtime - once they get paid you're SOL and they take 0 accountability.

Calahonda52

https://www.boards.ie/discussion/comment/120098660#Comment_120098660

This problem is compounded by the newer pumps which are called variable speed HPs leading to oversizing because they cant be arsed doing the design

SD_DRACULA

They say your pump needs to be running almost all the time (the less times the compressor restarts the more efficient it is)

Unfortunately I don't see pumps working with storage batteries (20kwh will be nowhere near to run the pump and the house in one day), it will just drain that very quickly and then you're being scalped at day rates.

Now I don't know what the pump consumption is once it gets to temp but from the mad values of kwh used per day by HP in the HP thread, I don't see batteries mixing with HPs unless you have 50kwh worth of them, maybe it works for @unkel so like 1 in 5 million 🤣

ColemanY2K

https://www.boards.ie/discussion/comment/120098888#Comment_120098888

I guess it very much depends how well insulated and airtight the house is. A passive house for example could have a 5kW or smaller HP. From spring to autumn it wouldn't come on if a big enough solar array and eddi was part of the setup.

How does having the heat pump off for 6 months affect the longevity of the unit? Instinctively I'd say it would increase the life of it but maybe not if sitting idle.

SD_DRACULA

https://www.boards.ie/discussion/comment/120099048#Comment_120099048

Can you get HPs that give you instant hot water like a combi boiler would?

I don't agree with heating a big tank of water that you may or may not use - wasted heat.

That way you'd have it during the year but I guess that's the opposite way that HP work as they have to do slow and low heat.

DC999

https://www.boards.ie/discussion/comment/120098660#Comment_120098660

Another option is go down the air con mini split route. That’s still an air to air heatpump afaik so supposed to have decent COP. And costs wayyyyy less than a normal heat pump. Cost is closer to gas boiler price afaik.  Heats and cools air only, not water. Not connected to rads, and not connected to hot water (so won’t heat water). So same setup as the air con in apartments in europe. Compressor out the back which connects to one of more wall mounted units inside. Plus handy for the (seldom) warm weather in Ireland to reduce the temp at night. We live beside a busy road so can’t open the windows at night (for noise more than fumes).

I’ll likely look into that when the gas boiler dies or is close to it. Won’t cover the whole house but the remainder could be electric rads. Need a lot of battery capacity for any electric heating so not running on expensive day rate.

Was a good Heat Geek video but can’t find it now. They did one on air con which I didn’t watch. But they did a follow up with an air con guru to correct some of their misconceptions. Difference is heating companies don’t fit them as air con uses refrigerants, not  gas mains, and there are no water pipes. So need to be refrigerant qualified afaik. Heat Geeks fella didn’t realise air con = air to air heatpump, nor did I.

This fella got one to supplement his other heating and raves about it. He’s electric rads in places and replaces his oil boiler. Toshiba Air to Air Heat pump (A2A) - Probably one of the best heating systems you can install - YouTube

Seems a decent setup if you’re ok to have more than 1 type of heating (which I would be as using electric rads in parts of the house for 1st time this year as well as gas boiler).

@unkel, did you get a mini split air con unit last year? Think I remember you saying you might or where looking at it

ColemanY2K

https://www.boards.ie/discussion/comment/120099153#Comment_120099153

I don't believe there is a HP on the market that can give you instant hot water.

Just realised an error in my original post. The HP would be needed to heat the cylinder to provide hot water for the taps/showers on the days the array isn't providing sufficient power via eddi to heat the tank.

While I see your argument about wasted energy heating a tank, that energy isn't necessarily wasted in a passive house. The heat loss from the tank will contribute to space heating which in theory could reduce the space heating burden on the HP.

ColemanY2K

https://www.saturnsales.co.uk/Panasonic-Aquarea-Radiator-PAW-AAIR-200.html#:~:text=Panasonic%20have%20a%20new%20range,c%20to%2045%C2%B0c.

https://www.boards.ie/discussion/comment/120099196#Comment_120099196

I looked at a similar system - albeit water based - from Panasonic. An ASHP connected to a cylinder for hot water and a fan assisted radiator for space heating. For passive or NZEB houses 1 fan assisted radiator could do the job depending on the size of the home. It too can work in reverse in the summer to provide cooling.

graememk

https://www.boards.ie/discussion/comment/120099508#Comment_120099508

even in a normal house its not wasted either.

Although the heat loss on the new cyclinders is very little, even at high temperatures. Theres more loss from the pipework coming out of the tank

DC999

https://www.boards.ie/discussion/comment/120099527#Comment_120099527

Interesting. Never saw that type of rad before. Looks like an electric one but is water rad with 4 speed fans. Fan assisting would help boost the convection. So even at the lower temp the rad runs, it would be getting moving more hot air upwards from the rad. And says it can cool too.

Heat Geeks did something on that afaik. Normal rad with fans at bottom to try cool a room. Did sfa as far as I recall, but was only half paying attention. But was a very cheap and cheerful stab at it. They did it in a small bathroom.

For cooling how would it work? Put cool water in rad and then it that 'radiates' into the room colling the warm air? But if a rad takes up a tiny % of volume in a room, I struggle to see how it’s gonna do much. Not being critical, just don’t get how it’s supposed to work. Difference with an air con unit is the amount of air it pushes out per min would be higher. And if it cools from the roof down, the air at the top causes a cool convention of air dropping downwards.   

ColemanY2K

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

I haven't looked into the technology behind it but do recall reading an additional condensate pipe was needed for the cooling function to work.

Snip below with further detail. I was wanting to go for it but the Mrs wanted a polished concrete floor and I feared without underfloor heating the screed would feel cold plus the plumber looked at me like I had two heads when I suggested it lol.

graememk

https://www.boards.ie/discussion/comment/120099654#Comment_120099654

That is interesting. Good if your space contstrained re Rad size.

Have you seen the heat geek where they did a DIY of that, Said condensate is something to be very wary of, Esp if running under the dew point.

ColemanY2K

https://www.boards.ie/discussion/comment/120099696#Comment_120099696

No I haven't. The cooling function wouldn't be something I'd be too worried about anyway. Getting the heating right a lot more important.

unkel

https://www.boards.ie/discussion/comment/120098888#Comment_120098888

I've already completely dismissed the idea of installing a full heat pump system. Lots and lots of money wasted on labour (and profit) retro-fitting. Then you end up with a system that will cost you more to run than gas / oil, if we end up paying 50c day rate electricity.

No way Jose, I'll have 45kWh of batteries within the next couple months, but even that simply isn't anywhere near big enough for heating on a cold day (never mind the rest of my electricity needs) On new (passive) houses and on very well insulated / retrofitted houses, it's a no brainer. For the rest of us not so much

unkel

@DC999 - not yet, but it's my most likely install when I have to replace my condensing gas boiler, that is nearly 10 years old now. Two large mini splits in the 2 biggest rooms on the ground floor. Then far IR panels in shed and attic (as I use now) and perhaps in the bathrooms. That will be it. I already heat all water with electric.

DC999

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

+1 for me on that. Our leaky gaff was 'born' in 1940s. So heatpump 'readiness' is wild money. I'd love an A rated new build, but that's not what we have :) We're using a mix of far IR panel, electric rads and gas boiler at mo. And house is at perfect temp in each room and we've halved our gas usage V last winter. So we're trying stuff and finding what works. It's a little clunky as don't just have a single Nest app to change the heating. But works for us

unkel

Snap. Trying to settle in this winter, see what works best, the far IR panels are new here. It's a combo of gas and electricity. Using a lot less gas than in the past and the electricity for heating is coming almost entirely from night rate (and some from solar)

SD_DRACULA

It would be very hard for me to move away from the comforts of a combi boiler, for the likes of instant (and fresh) hot water for showers.

This https://sunamp.com/en-gb/products/thermino-ipv/ will do very nicely for pv/boiler/cheap night rate combo but installers in Ireland don't have a clue about the tech.

https://www.boards.ie/discussion/comment/120099196#Comment_120099196

I was thinking about something like this alright https://www.buyitdirect.ie/p/multi-split-27000-btu-smartapp-wifi-inverter-wall-air-conditioner-with-3x-9000-btu-indoor-units-to-a-single-outdoor-unit-iqool-3ms9k9k9k but the A2A COP is way worse than A2W and I think you'll need two of these for the whole house probably but it will give you true zoned control and also help for those 2 scorching weeks we get once a year 😂

Each unit can pull 3kw so 18kw o'clock easily from these.

monkeybutter

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

this seems like nuts power useage no? More than 45kwhs per day?

What kind of multiplication factor are people actually getting and does it make more sense with water to water?

The only people I know who fitted did go water to water because of this

Calahonda52

What is the COP of what are referred to here as "far IR panels"?

Are there such things as "near IR panels"?

cruizer101

https://www.boards.ie/discussion/comment/120101674#Comment_120101674

The near and far just refers to the wavelength of the infra red light, near is closer to visible light its not in relation to at what distance the panels are effective or anything like that. Link here with some more details https://www.scottishenergysaving.co.uk/whats-the-difference-between-near-mid-and-far-infrared-heat/

Re COP, its just 1, electric heaters convert 100% of electricity to heat. That said they potentially can be more efficient than a convection heater in that you may not need the same output to feel as warm as the convection heater has to heat all the air in the room the panel just heats you. I've no direct experience but have looked into them a bit as considering one for my home office for heating during the day.

DC999

https://www.boards.ie/discussion/comment/120102038#Comment_120102038

Spot on description of infrared heater. I’ve one for the WFH room and I like it. For me it’s more comfortable than other forms of heating including oil filled electric rad. It heats me, not the air. They really supplement heating, not replace it. Start from around €120 euro for the basic ones, more depending on the wattage and bells and whistles.

Uses a little less electricity than an oil filled electric rad in the WFH room. It’s a cold room with old windows that doesn’t see any solar gain and loses a lot of heat. Means I don’t need the room to be as warm as I’m in the line of the heat. And drafts don’t affect it. I can even open the window a crack and still be warm – which takes getting used to 😊

I got a 350W one and it’s fine. That’s likely on the small size for some but ok for me as it’s on the wall close to me.

Mine is on or off only, can’t adjust the wattage. But it does turn off when reaches the temp you set. Thermostat on it is a very crude. It’s not the temp it thinks it the sensor is on the side of it (so it’s hotter than the room). But once you work out the ‘offset’ it’s ok. I wanted a small wattages one as have solar but no battery so wanted to use the solar excess for heating.

They work for places you stand or sit at – as in you’re not moving so in the line of the heat. Only other place we could use one would be the sitting room. But would need to be roof mounted over the sofa due to the room setup. That’s the most efficient setup some manufactures suggest, but need to run a cable down the wall to a socket or get a spark to add a spur.

Some have them in the bathroom to replace the mirror over the sink. But that wouldn’t heat our shower area, so no gain for us there.

Calahonda52

Thank you both for the comprehensive and helpful replies, such a rarity here.

Have seen them roof mounted in a warehouse in Dublin, hot water fed, as you say heat the person not the air

cruizer101

You can already get fans that can be added to existing radiators to increase the output, radfan and speedcomfort are 2 I've come across. I've looked into them a bit but havn't been able to find any decent figures on the output increase.

There are already stats on how the output decreases with lower deltaT, image below shows it.

It would be great to be able to see the increase based on forced convection. Lets say you have a rad with 2kW output at 50deltaT running off a conventional boiler than heats the room more than sufficiently. You want to put in Heat pump but the lower running temp means you have only a deltaT of 20 so the output is 600W, not enough for the room. What if using fans you could bring that back up to 1.2kW. That might be enough heat for the room without having to get a bigger rad if you run it constantly instead of cycling at 2kW. It could make Heat pumps much more attractive if you didn't have to replace the radiators.

I did try see how much of a difference it would make but trying to find the heat transfer coefficients for free convection and force convection is hard as I think the radiator geometry would come into play. Best way would probably be experiment measuring the temp in and temp out of radiator with a fixed deltaT and flow rate with fans and without. Bit much for me to bother but easy enough setup for a business or university with an interest in it.

THE ALM

Interesting read, thanks for sharing.

Is an area we are looking at at the minute as we are looking to replace the boiler.

Reading various forums and trying to educate myself it seems the main gripe is the design and installation of a heat pump so it makes you wonder if you get someone in have they designed it properly. If anyone can recommend someone then let me know.

I have carried out some heat loss calculations so will be interesting to see how they compare.

the_amazing_raisin

https://www.boards.ie/discussion/comment/120098806#Comment_120098806

Tbh I don't think that it's a case they aren't arsed, the installers aren't heating engineers, they're not really qualified to do the design to any degree of depth

From what I've seen, they seem to have a basic cookie cutter system design that they put into all houses. Bigger houses, scale the system up a bit, etc.

The manufacturers seem to try and support this, they make standard systems and fairly simple online calculators that just spit out a system spec

The problem is without someone qualified double checking the system, it can end up pretty poorly optimised. Installers could probably get away with this back in the days of oil and gas. You can kind of balls up an oil boiler to some degree but if it's putting out water at 70C then the house will be warm regardless and the customer probably won't know any better

With heat pumps, having an efficient design is critical. I think this has led to some pretty terrible design decisions and bad installations

graememk

https://www.boards.ie/discussion/comment/120104877#Comment_120104877

I wonder how many people actually realised how much energy is being used to keep the house warm? Actually seeing the electric bill, vs getting 2-3 fills of oil a year. Which has doubled in price also..

the_amazing_raisin

https://www.boards.ie/discussion/comment/120105220#Comment_120105220

Absolutely, people tend to compare the price of fuel but they don't compare the consumption. One person might be using 20l of oil a day and think it's fine until they see someone using 10l per day for a similar type of house

I'm starting to subscribe to the idea that the best thermal store is the house itself. There's a lot of stuff in the house which can absorb thermal energy, furniture, concrete flooring as well as the structure of the house itself

That should provide a reasonable buffer if the house is well insulated.

It's interesting how a buffer tank is supposed to stop the heat pump cycling but has been shown to actually increase it

I still think there's value in using a buffer that you can zone out using valves for a heating system that can't provide heating on demand, like solar. That'll give you the ability to store energy when it's abundant and you can cut it off from the heat pump when it isn't needed

unkel

https://www.boards.ie/discussion/comment/120105220#Comment_120105220

When I tried to heat the house purely with electric (and trying to avoid the peak rates), the cold snap put my face right into the numbers. Which are a lot higher than I thought they were. With gas / oil being like 3-5c per kWh like they were for years up to about a year ago, you didn't really notice it. But you do know

I've already heard from several people around me with modest houses having got a €1000 gas bill the last time. And electricity bills not far off (before the govt subsidy)