Heat Pumps - post here.

MacronvFrugals

I rent a new build apartment that uses a Comfortzone EX35 exhaust air heat pump.

All was going well until two weeks ago when an error appeared "Compressor Function Error", directly after this our daily electricity bill rose 75%, maybe 2 weeks after it has seemed to drop down to a bit less than normal usage but the apartment doesent quite seem as warm. Clothes take longer to dry etc.

The hot water still heats ok but the system seems to be not operating as expected, the landlord is being really slow helping so i said i'd ask here if anyone knows what this could be.

graememk

https://www.boards.ie/discussion/comment/119743235#Comment_119743235

I think the error points to what's going on, something to do with the compressor has failed, and is fallen back to the backup heater (which is just an immersion)

Need to get that looked at ASAP, your heating could end up costing you 3-4x as much!

MacronvFrugals

https://www.boards.ie/discussion/comment/119743706#Comment_119743706

Hi graememk,

Thanks for the reply its appreciated. We have a smart meter and for about a week post error the usage did indeed skyrocket as you mention but now it has dropped to below even summer KWH numbers which makes me think something is not right. The apartment is A2 rated and feels ok but not nice and warm.The error still appears on the HP.

BoardsMember

https://www.boards.ie/discussion/comment/119742965#Comment_119742965

Thanks, that's really helpful.

If ur using the combi boiler for both UFH and Hot Water how do u know what ur spend on hot water is?

Also, how does it work that u feed the UFH to 30, but hot water would be needed much hotter? I'm not great on the tech side of plumbing, manifolds, adding cold water in to bring down temp etc. Can it be efficient with combi heating to required hot water temp and them cooling it down to temp that the UFH needs? I'd also be running rads upstairs.

Paul Kiernan

https://www.boards.ie/discussion/comment/119748313#Comment_119748313

The heating is off in Summer so all the usage is DHW!

The combi boiler has 2 independent circuits, one for CH and the other for DHW. When you turn on a hot tap a flow sensor diverts the CH water into a secondary water to water heat exchanger and heats the DHW to the required dial controlled temperature, say 60 degrees.

For normal CH use the boiler just heats the water to the required (set by another dial) temperature, say 30 degrees, and that water goes straight into the UFH manifolds. Boilers that are used to heat an immersion need to be much hotter, say 60 degrees, and in that case a mixer must be used to reduce the temperature as it's too hot for the UFH. This in itself isn't inefficient but the boiler gets less efficient as the water temperature increases.

BoardsMember

https://www.boards.ie/discussion/comment/119748356#Comment_119748356

So interesting, thanks!

Curiousness99

https://www.boards.ie/discussion/comment/119665593#Comment_119665593

I paid €400 for one and was quoted 550 by another company, not sure why but the company I went with also did an initial BER, I believe I need them to do another BER once the heat pump is installed so probably another 150 it 200 to pay yet, house is big too which you’d think would bring the price up

ConorC1

Is there a way to take advantage of cheaper night rate electricity when using a heat pump with UFH? I have been told before just to set it at desired temperature and let it do it's thing. It's a A2 rated house so in general the temperature doesn't drop too much during the day when the ufh is off/not calling for heat... 1 or 2 degrees max.

Thanks

sydthebeat

https://www.boards.ie/discussion/comment/119770066#Comment_119770066

do you have either

(1) a night rate meter, or

(2) smart tariff meter set up for graduated tariffs?

ConorC1

https://www.boards.ie/discussion/comment/119770169#Comment_119770169

Smart meter with hourly readings viewable online. I'm on a day/night/peak plan with SSE. Night rate is from 11pm to 8am

graememk

https://www.boards.ie/discussion/comment/119770363#Comment_119770363

You could set a higher set point on the thermostat overnight and then back it off during the day... Although most people prefer a cooler bedroom...

It's worth a try anyway

Paul Kiernan

https://www.boards.ie/discussion/comment/119770066#Comment_119770066

From what you describe you should be able to get all the heat you need during your 9 hour night rate window. How you actually do it is another matter!

Thermostats and UFH don't really go well together due to the time lag so you can't use them in the traditional sense where the heat goes off when the room gets hot and vice versa. What sort of controllers have you? I'm using heatmiser stats and am still struggling to get everything to work as I want it! In some cases (bathrooms) I use them purely as a timer so heat comes on from 3am to 8am. In others I might set 18 degrees from 0100 to 0300, 19d from 0300 to 0400, 21d from 0400-0800 so on colder nights I get seven hours but only four hours if room stays warm.

However the one thing I'd certainly do is make sure it never comes on outside 11pm to 08am.

ConorC1

https://www.boards.ie/discussion/comment/119771522#Comment_119771522

That sounds like a plan. I have heatmiser stats as well. However there is only 1 on each floor (3 story terrace house built in 2020). The ground floor has UFH and the other 2 floors just have radiators. I rarely need to call for heat on the these 2 upper floors unless the bedrooms are particularly cold at night time. If so i just manually adjust the stats and the rooms heat up quick enough.

The only stat on the ground floor is in the living room which has a wooden floor. It's not ideal really as this room takes way longer to heat up compared to the kitchen (tiles) . I like your idea of the gradually increase in heat during the night if needed. What is the correct setting on the water temperature on the heatpump? Mine is currently at 40. I don't know did i ever change it. Can't remember

graememk

https://www.boards.ie/discussion/comment/119772556#Comment_119772556

Leave the temperature on the heat pump be, although the lower you can set it the more efficiently it will run.

redmagic68

https://www.boards.ie/discussion/comment/119770066#Comment_119770066

We heat the bedrooms to 19 degrees from 11-5am. The thermostats knock off the system once at 19. From 5am-8am I set it to 20 degrees. Unless someone leaves a door open or it’s really cold/windy out the room remains at 18-19 degrees. Rooms with greater travel can be a little harder to balance but again every zone is set for night time units only and it’s very rare it requires a day boost.

flow temps are 28 in the ufh and 55 for dhw. This is coming in currently at around €5 a day total cost but we use electricity for cooking also. Standard hourly load when the house is dormant is 0.4kw just for context.

graememk

https://www.boards.ie/discussion/comment/119772927#Comment_119772927

What unit rate are you on?

€5/ day isn't too harsh now that we're well into autumn

staples7

I have it timed for night rate. Releases heat during the day. Works a treat

BoardsMember

https://www.boards.ie/discussion/comment/119748356#Comment_119748356

Sorry, one last question on this. If you have a mixture of ufh and rads, does that mean there are 3 different temperatures being called for? Or do the rads just trigger the same call as the hot water?

Paul Kiernan

https://www.boards.ie/discussion/comment/119772556#Comment_119772556

Does the heat pump have separate circuits (at different temperatures) for the UFH and the Rads? I presume you have bathrooms on the upper floors that need heating? Regarding wooden floor v tiles it's just a time lag, heat will get out eventually! Just makes it harder to control!

If I was in your position I don't think I would ever need to put bedroom rads on as heat from below would heat them! The stats would then control the bathrooms but as a timer, not a thermostat! I presume you don't have stats on the rads?

Then for ground floor I'd run the heat at night so your floors are nice and warm underfoot all day and probably only cool down in the evening!

CHorn

Building new home, started Jan 2020, but with lockdowns and C!9 and you name it, it happened completion date now Feb 2023.

But looks like Solar Panel Grant will be extended in 2023 budget to cover 2400 of cost. Will extension also cover heat pump grant of 6500 (detached home)? Can't find any info anywhere on this.

ECO_Mental

https://www.boards.ie/discussion/comment/119774447#Comment_119774447

Don't think you will get a grant for solar PV for a new build house or any grants if you are building a new house. All these grants are for retrofits to bring the existing old housing stock up to be more efficient.

I just built a house and moved in last year and didn't get any grants...that's not saying I f**ked up and missed out on something

Mr Q

https://www.boards.ie/discussion/comment/119774781#Comment_119774781

Depends when the meter went in for the solar grant I think. It does mention built and occupied before 2021 but I assume if you got your meter in 2020 you would qualify. Doubt they check to much details.

So possible that is in long enough for a grant but unlikely.

Mr Q

Do people heating the house enough for the day while on night rate not find the house too warm at night?

In previous years I always let the HP do its own thing over the 24 hours as I found this most efficient. But obviously the the unit rates were not as high.

Nelbert

I'm trying to just heat water in the night period but once I heat the floor downstairs at all the house is warm for the day with the heat gain from the sun.

Last winter there was some calls for heat during the day but not many and we've gotten a sedum roof on the main living area since then so heat retention is improved further so hoping for little to no day time calls for heat this winter.

It's a difficult balance to save money but not end up too warm.... (If you overshoot and the sun is strong on a given day the kitchen becomes a sweat box).

redmagic68

https://www.boards.ie/discussion/comment/119773162#Comment_119773162

Energia ev plan signed up at the start of September.

ConorC1

https://www.boards.ie/discussion/comment/119774072#Comment_119774072

Yes the heat pump has separate circuits. Bathroom usage is minimal so don't bother heating them regularly. With only 3 stats in the whole house (none on rads) it's hard to heat individual rooms to a desired temperature so I Just leave them.

If the ufh knocks off at 8am would it still use power for a while after that to bring the water back to it's set temperature of 40 degrees? What is your ufh water temperature set at?

CHorn

Quick Q: when calculating square metres in a house to calculate size of heat pump needed, do you use square metres of footprint of the house or the square metres on each floor? I'm guessing total all floors, but can't find for sure.

More generally I'm trying to calculate what I might need for a new build using a Samsung EHS Monobloc (Gen6) like these: https://static1.squarespace.com/static/5894a3b0be659481ff6f152c/t/5fa2833be20cf768bd007fcd/1604485948079/Samsung+EHS+Monobloc+Gen+6+Nov+2020.pdf

I've got two floors: 120m2 and 100m2, total 220m2 top spec insulation for completely new build, any thoughts/ideas/suggestions on what's appropriate and/or if this Samsung is a good choice?

ConorC1

https://www.boards.ie/discussion/comment/119772927#Comment_119772927

My ufh heat is set at 40. Did you set yours at 28? Seems to be a big variation here on what different people have it set at

Paul Kiernan

I've my UFH set to 30 degrees at the moment but as it gets colder I'll probably turn it up maybe to 40. My UFH is unusual in that it's in the concrete slab which is 4"-7" deep. So it's very slow to heat up and cool down. So slow, in fact, that if I set the stat to required temp it'll come on for maybe 12 hours or so then stay off for 36. In that time the room will vary from maybe a degree above to a degree below the desired temp which isn't ideal! So I can't just set the desired temp and forget about it.

UID0

https://www.boards.ie/discussion/comment/119782415#Comment_119782415

The square metres is only useful for giving an indicative sizing of the heat pump. You need to do (or get someone to do) the full heat loss calculation for your house, which looks at heat loss through the walls, floor, roof, windows, doors in the house, and is calculated for each room. You also look at the internal volume of the house and the number of air changes.

The rule of thumb says that for your house, an 8kW heat pump would be about right, but it depends on your actual house. That could end up being undersized.

There is a heat loss calculator here (GitHub - TrystanLea/heatlossjs: Simple room by room heat loss calculator) that would allow you to play around with the parameters, but I don't see any way to specify that you are using MVHR (could be simulated by lowering the air changes per hour).

On the Samsung Heat Pump, here's a guy in Wales who installed it himself (How I fitted an Air Source Heat Pump ASHP - YouTube) and here's his energy monitoring for it (Emoncms - app view dashboard)