Heat Pumps - post here.

JayBee66

https://www.boards.ie/discussion/comment/120579408#Comment_120579408

That seems like a big heat pump for a house that size and with such a low HLI and good air retention.

As we don't want to heat the whole house and just get 3 heating units (lounge, office and hall - which will serve the rest of the house to about 17C,) I'm hoping for a smaller heat pump in the 8KW range.

However, I'd rather get a little too much rather than not enough.

THE ALM

https://www.boards.ie/discussion/comment/120579594#Comment_120579594

That was my thinking as well, was expecting in the 8kW size.

Not sure how they extrapolate the figures to get to 11kW.

DC999

https://www.boards.ie/discussion/comment/120579915#Comment_120579915

I heated downstairs in our (small) house with 3kW of electric rads for most the winter. Granted that was colder than most would like. Gas boiler only came on 3 hours a day max. Rest was electric rads. I don’t have a heatpump but wanted to get a sense of the heat needed in the room. Know I know the watts we need to heat the rooms. Doing that meant the electric rads needed to run pretty much all the day (like a heatpump).

We’re in a tiny house with a large 15kW gas boiler. We never questioned the size of it, we just got an installer to supply and fit all the years ago. Are they simply providing big systems as that’s what the heating industry has always done? Or is there a reason that bigger is better in terms of not cycling the system or overworking it which could impact it longer term? Won’t pretend to know much about heatpumps. 

Or do they leave capacity in case people need to crank up the heat all day like the 'beast from the east' freeze 10+ years ago? The once a decade cold snaps? If so, get a plug in rad in the room and will supplement the heat.

the_amazing_raisin

https://www.boards.ie/discussion/comment/120580564#Comment_120580564

I think it's a case that installers are going for a more powerful heat pump as some insurance against the house feeling cold, same as they did with gas and oil boilers for years

If they wanted to avoid cycling (which seems to be the ideal way to run a heat pump) then you'd presumably want the smallest pump possible to maintain the lowest flow temp you need

Now I'll admit I don't know the math that goes into sizing a heating system, so perhaps there's something that a larger pump is needed for a lower flow temp

But it seems to me that efficiency is being sacrificed to stop the installer getting complaints about a cold house. Instead we'll just end up with more complaints online about how heat pumps are a apparently a scam

graememk

https://www.boards.ie/discussion/comment/120580564#Comment_120580564

gas boilers, seem to be generally thrown in with a bit of "better look at it than look for it"

And that's how houses were heated, let it cool and then blast it.

The condensing gas boilers did complicate things a bit, but how many were actually installed that they went into condensing mode (a low return temperature)

Boilers now can modulate to not burn as hard to try and stay in condensing mode.

Cycling of a gas boiler isn't really too much of an issue though, but on a heatpump it can really hurt efficiency, if a heatpump is too big (or can't down rate enough) it can put too much heat into the system and has to shutdown.

Too much heat doesn't mean the house is too hot it's more if the radiators (or not enough radiators on) aren't big enough to dissipate the heat and the return is too hot.

The heatloss calculation is done at an outside temperature of -3c.

Here's someone who's done a DIY heatpump (one of the people from openenergymonitor)

https://youtu.be/Hyv_vQEvHgo

The make I'm looking into is ecoforest, (for the r290 ones) and the 8kw one can down rate to 1kw but the 12 can only go as low as 3kw.

DC999

https://www.boards.ie/discussion/comment/120580845#Comment_120580845

Wow, as low as 1kW is unreal. Would be good for early autumn and late spring. Want a little heat but don't need 3kW in the house.

JayBee66

My biggest understanding of heat pumps is that I don't understand heat pumps. I know it's similar to a fridge in reverse. After that I have no idea about sizing and performance. I feel that a few installers might be the same so I am wary of all of them. Greening your home still feels that it is at the Wild West stage.

So far, I have self-managed the retrofit of our house (insulation, triple glazing and PV) from C3 to B1 with just heating and ventilation to go. I am tempted to put in HRV myself. A heat pump would be too difficult and I feel as though I'd rather put in resistive and FIR heaters and accept that I am going to need more electricity to power them.

Considering that I am well past the halfway point in my life, the savings from going for resistive and FIR heaters might just pay for all the additional electricity.

DC999

https://www.boards.ie/discussion/comment/120580845#Comment_120580845

Watched the video. Hat’s off. That’s the setup many should be aiming for - he's made each part super efficient. He's no deep retro fit and still running a 5kW system. He’s 3 rads in sitting room which most wouldn’t be happy with (and takes up a lot of space). But means he can run something like as low as 30C in the rads which is lower than I would have known could heat the house - so his COP stays really high. 

He’s showed me that our little leaky 2 bed with a low BER can work with a small heatpump. But with…a lot of design thought going into it. He’s stats you can read: Emoncms - app view. Ok, not gonna show much decent info for April (last month) but his COP since it went live in Aug 2022 is 4.26. Which is savage as means the winters didn’t drag it down massively.

the_amazing_raisin

https://www.boards.ie/discussion/comment/120580845#Comment_120580845

That is a fantastic video, I've always thought the open energy monitor project is one of the best out there

For anyone interested, here's the heating demand calculator linked from the video

https://openenergymonitor.org/heatlossjs/

It's definitely a tad more complicated than your typical online calculator. I'll be giving it a go myself to try and see how my current heat pump compares to what I could achieve

THE ALM

It is a such a minefield out there and although heat pumps have been around for years and work no problem I feel that they are a relatively new concept in Ireland and a bit of work still needs to be done on the efficient design and install of them, we are still used to sticking in a big oil/gas boiler and whacking it up to 70+°.

Like @JayBee66 we have done a lot of work upgrading the fabric of the building and now down to the heating and ventilation, I'll probably tackle a MHRV system install myself as the air tightness test has us well below the threshold for having one.

I have completed the SEAI heat loss calculator and will go through the one linked in openenergymonitor to see how they compare. I have completed the BER Assessor course so have a good grasp on our house and the sort of person who does a lot of research before jumping into something.

We have been running the oil boiler at its lowest setting for most of the winter and have been coping ok, just boosting the hot water temp once in a while for legionella. Our biggest space is a open plan living, dining and kitchen area with vaulted ceilings and we installed a 6kW pellet stove which we run at its lowest setting, about 3kW, during the coldest months and that keep the space toasty and a lot easier to maintain than the solid fuel stove I took out.

So with all that I feel we are in a good place for a heat pump and just need to find the right person for the job. In my mind, maybe naively, it shouldn't be such a big job to install them and it is the tweaking etc. afterwards to get it running efficiently that is the problem and where not a lot of time is spent to get this optimal.

EDIT: Looking at the pump sizing I wonder is it a case of taking the heat demand of 6.6kW and multiplying that out with the HLI of 1.78 to give the heat pump size of 11kW, which would kind of make sense.

THE ALM

Following on from that video I went to the heatpunk.co.uk website and set up an account. This seems to be part of the midsummer renewables group and links to there website with prices (UK) etc for the heat pump.

You can layout a plan of your house, adding windows, doors and radiators etc and it will give you a recommendation for a heat pump. Takes a bit of setting out but nothing too complicated and it gave me a size of 10kW, so all coming in at around the same as other calculations.

I think at this stage I have my homework done so time to find a few good installers and get quotes.

the_amazing_raisin

I found this article linked in the video and I think it's absolute gold for explaining how a heat pump is sized

https://energy-stats.uk/what-size-heat-pump/

The answer is, as expected, that it depends on a lot of factors and there's a lot of calculations involved

I have to say, between the guys from Heat Geeks and Open Energy Monitor, there's an absolute wealth of information out there on heating system design

I know there's a lot of folks out there who are confused about what size heat pump they need, and while I don't think designing your own system is for everyone, it's probably worthwhile for folks to do their own heat loss analysis and see what conclusions they can draw

For example if an installer says you need a 10kW heat pump and don't need any new radiators or pipework, and then you crunch the numbers and figure out you'd be fine with a 6kW heat pump with new emitters then it's certainly going to make you ask some questions if that installer and how they arrived at that conclusion

I think it also goes to explain some of the reasoning behind why bigger radiators and pipework is better for a heat pump, and why a conversion job costs so much

I'd personally be tempted to do the pipework and radiator work myself. It's pretty involved work but you could save some serious labour costs by doing it yourself and you could do it over a few weekends in summer when you don't need the heating

THE ALM

https://www.boards.ie/discussion/comment/120596412#Comment_120596412

Thanks for that, lots of info to go through there.

Like you I'd probably do the radiator work myself, wouldn't be the first time draining the system and installing a new radiator.

the_amazing_raisin

https://www.boards.ie/discussion/comment/120598655#Comment_120598655

I haven't done much by way of pipework myself but it doesn't seem like there's a great mystery to it. Looking at soldering pipes online it seems the kind of thing that you could learn well enough after and hour or so of practice

I already have a heat pump so I probably wouldn't need to upgrade all the pipework

However I do have this dream of going from radiators to underfloor heating and fan cassettes upstairs. I don't like radiators and I'd like to eventually get a heat pump with cooling, which kind of necessitates some degree of fan assistance

I'm also fairly convinced that the heat pump I got was optimised for the installers profit margin above all other things, so I'm convinced that I could optimise it further

JayBee66

If you don't like the idea of soldering (I thought it was brazing) you could use press-fit or compression fittings. Our house is pex pipe under the concrete floor and then pex to copper compression fittings, then a short length of copper pipe joining to the radiator valves with metal to metal compression fittings. I only solder electronics. I've never brazed copper pipes, just used compression fittings.

DC999

https://www.boards.ie/discussion/comment/120599704#Comment_120599704

What's a fan cassette for heating?

the_amazing_raisin

https://www.boards.ie/discussion/comment/120600195#Comment_120600195

This kind of yolk (scroll down near the bottom to the concealed ones)

https://www.daikin.ie/en_gb/product-group/daikin-altherma-hpc.html#tabs-121f9a26f2-item-97d6798dd8-tab

EDIT: Found a better link

https://www.daikin.ie/en_gb/products/product.html/FWXM-ATV3.html

They're pricier than a radiator obviously, but allows for cooling and is concealed. I'd probably only put them in the bedrooms where they're needed most

paddyman

https://www.boards.ie/discussion/comment/120571824#Comment_120571824

Hi guys - just giving an update. I had the installer push back on the manufacturer recommendation of 10KW heat pump and they agreed they made a mistake.

"Hi xxx 

 Hi xxxx,

 I used the current HLI instead of the HLI after work done. Using the after work they will indeed need a 5.5kw load which would be a 6kw heat pump. Apologies for the misunderstanding.

"

So i am much happier with this. :)

Paddy

the_amazing_raisin

Has anyone gotten those heat pump monitors?

https://docs.openenergymonitor.org/applications/heatpump.html

They're not exactly cheap so I'm not planning to recoup the costs, but the controller on my heat pump is fairly garbage and doesn't show any useful data other than on/off/error

So it'd be nice to see what CoP I'm getting as I suspect it's lower than claimed 4.0 and if possible I'd like to optimise it for some energy savings

unkel

https://www.boards.ie/discussion/comment/120580845#Comment_120580845

That's an amazing video. But the amount of work involved and even the cost of materials used sends shivers down my spine. If I hadn't made my mind up already, I have now. I will get an extremely less complicated air to air heat pump instead of air to water. No radiator replacements, no pipes in the floors and walls throughout the house. Simple air units indoors right beside outdoor pump with minimum pipe

Probably save a good €7-8k in install / retrofit costs after the grant (which I won't get), but will probably lose €500-€600 a year in efficiency loss because of a COP of maybe around 2 instead of 3-4

Also what's the story with not heating water above 45C? That is not quite hot enough for people who like hot showers / baths - like all 4 of them indoors in my place 😂 I guess if you go to 50C you will lose a lot on your COP?

graememk

Yeah the hotter the water the lower the cop, how hot is the actual shower water though?

If you have a big enough tank, to do what you want, why heat it hotter?

Still better than using an immersion to heat it though!

unkel

https://www.boards.ie/discussion/comment/120605924#Comment_120605924

Not better, just cheaper as the COP of immersion heating is only 1 😂 It's much better for that €8k to stay in my pocket though 😂 And I already have large solar thermal and solar PV systems in place that help a lot with hot water heating for most months of the year except winter.

Let's just say that at 45C actual shower water, I won't get any complaints (just) but it's simply not quite as hot as they like it.

unkel

Interesting product, basically a portable heat pump from Ecoflow. Claimed COP of 2, but priced at $1k without a battery. Claimed 6100BTU in heating, had to look that up and it's 1.8kW

https://www.youtube.com/watch?v=MgJ3-Wr-q2I

So with that claimed COP it would actually consume just 0.9kW. Does not compute though. The battery is only 1.1kWh yet he claims it can last up to 8 hours. Yeah, if you dial it right back to next to nothing maybe.

Still an interesting unit all the same. Maybe this is the future of cheap yet efficient home heating? With a heat output of 1.8kW, I would only need two of these units to mostly heat my house. Added by a few far infrared panels around the place particularly on the coldest of days. What is obviously very attractive is the zero install costs, just plug and play.

graememk

Paying for portability and size.

But it's just one of these

https://www.buyitdirect.ie/p/12000-btu-portable-air-conditioner-for-rooms-up-to-30-sqm-p12c

the_amazing_raisin

https://www.boards.ie/discussion/comment/120605883#Comment_120605883

Surely you'd still have to plumb the refrigerant pipes through the house? The outdoor unit is usually on the south wall so you'd need to bring refrigerant to the north facing rooms

PCDub

https://www.boards.ie/discussion/comment/120606401#Comment_120606401

Does that unit also heat aswell as cool?

Good review of that new ecoflow unit by hobotech on youtube.

graememk

https://www.boards.ie/discussion/comment/120606471#Comment_120606471

That one doesn't..

This one looks like it does.

https://www.buyitdirect.ie/p/airflex-14000-btu-4kw-portable-air-conditioner-with-heat-pump-for-rooms-up-to-38-sq-mtrs-wifi-airflex15w

Not a recommendation just looking them up online. But it's pretty basic tech now.

Ecoflow stuff is expensive but your paying for portability, size and convenience.

If buying for a house, I'd go for a "mains powered one"

Venting these can be an issue too but chatting to others, a chimney could work quite well!

JayBee66

https://www.boards.ie/discussion/comment/120606493#Comment_120606493

A chap on YouTube used the electriQ to build a system for his home heating. It reminds me of Terry Gilliam's movie Brazil.

https://www.youtube.com/watch?v=V_LTyeywOiQ

unkel

https://www.boards.ie/discussion/comment/120606493#Comment_120606493

Was hoping / expecting there would be more powerful, yet cheaper ones! Why would you need to vent one? Aren't they a closed system, like a fridge?

Edit: from the ad, it states "Please note that the heat pump mobile air conditioners will need to be vented out in heating mode, ideally through the wall. By properly venting them you will expel cold air from your room while efficiently heating it. The unit will not need venting in dehumidifier mode."

It comes with a 1.5m length, 15cm diameter hose that needs to be connected to the outside for heating mode

Dozz

https://www.boards.ie/discussion/comment/120606671#Comment_120606671

Jaysus thats some ball of sh!te 🤣