Should there not be an open circuit rad like say a towel rail in the bathroom and also a bypass circuit so the circulation pump doesn’t stall?
I think getting a good installer is key. One that is willing to walk away if they don’t think it will work for your house. Though I suspect they will work in more situations than perhaps people think, provided they are properly sized and installed.
Our installer commissioned what seemed to me to be thorough set of heat loss calculations. They were carried out by an ‘independent’ surveyor and who also provided an EPC as part of the survey. The calculations were done for each room which allows them to specify the radiator requirements for each room. Then they were are totalled for the house to specify the heat pump. Our house was built in 1996 and was rated D on the EPC certificate. It was recommended that we change half of our radiators… as part of closing the deal the installer agreed to help with the cost for the other half. I’m glad we did because the radiators seem to be really effect, often running at 35°c and below, but still giving off convect a noticeable amount of heat - constantly.
We run the heat pump, 21 hours per hours a day on weather compensation mode. It was 24 hours a day until we recently moved to the Agile tariff. It now switches off between 4pm and 7pm to avoid the peak tariff/cost. Having it switched off for that 3 hour period doesn’t noticeably effect the temperature in the house.
Before we moved to the agile tariffs, I’d say the running costs we just under those for our old boiler, but that was an old glow worm boiler. With the new agile tariff, with avoiding peak tariff time, so far it looks like we’re going to come in a between 50%-60% of the run cost of the previous tariff. With all of the windy weather on Saturday, the cost went negative, so I took the opportunity to run a pyro clean on our oven. The days total energy costs were 9.48 pence. Of course it was particularly windy over the weekend. The cost for Sunday hasn’t come in yet, but I expect that to look good too.
We have a wood burning stove in the living room, but we haven’t used it much since the ASHP was installed as the living room is always toasty now. Which is a bit of a shame in some ways.
We also have our TVRs set to max, but have used the lock-valves to regulate relative temperatures between the rooms. So in our bedroom the lock-valve is set to almost closed as we like it pretty cool. In the areas where we want most heat (bathrooms) they’re set to wide open.
I had to reduce the radiator/heatpump flow rate to get a decent delta t. I’m now achieving Coefficient of Performance (COP) of upto 4.5. It’s now at an average of 3.1 and rising, since installation last February.
Our heat pump starts to run defrost cycles when the outside temperature is about 1°c and below. It does seem to effect efficiency, but doesn’t seem to effect the ability of the heat-pump to keep the house warm.
We got a new super efficient oil fired boiler so we don’t have an air sourced heat pump, but some of our neghboughs have converted from electrical storage heaters and old style oil boilers to heat pumps - and my daughter has a heat pump.
The only comment with conversion is that one needs to typically up size radiators because of the lower heat output.
My daughters house has floor heating and radiators for upstairs and was a new house designed for air source heat pumps.
However the only concern appears to be noise. One of our neighbours had the air source heat pump added to an outbuilding away from the house. Another neighbour had an acoustic baffle built around it and it was situated away from the house in a side lawn.
My daughter’s heat pump is attached to the back wall of the house and they do hear it and it is noticeable. They also now have built an acoustic barrier around their newish heat pump. They live in a rural location.
So hopefully as they develop, the noise element will be cracked - probably more an issue in quiet rural or dense environments rather than more noisy urban/suburban environments. And also I hear the heat temperature outputs are starting to significantly improve with recent innovations.
Though when I looked into it two years ago building regulations for locations for ASHP are quite specific because of the noise matter - away from property boundaries - on a plain wall with minimal other acoustic reflective surfaces nearby if can’t be standalone with acoustic baffle, and also away from being near or below any bedroom windows
I think there are tricks installers can play. For instance one after quoting decided to add another £9k to rip out perfectly good 22mm main pipe runs that he didn’t even inspect. Needless to say I walked away!
One empirical test anyone can do is to reduce the flow temperature of a gas system down to 40c or lower and see whether the rads develop cold areas at the bottom. Alternatively use an infrared camera to get temperature measurements.
I found that trying to achieve 24/7 running was not worth the effort. With nights near freezing the bedrooms can drop up to 3c overnight. From December to February I did run the heating from 2-5am when on the cheap rate. If I switch to Agile from Flux I could probably lengthen that.
If I were you I would fit metering on the heat pump circuit to know the energy used. It is good that Agile is cheap, but you need to be able to calculate your cost in case the tariff is withdrawn.
Phil
Ours is on a gable end wall with no windows, and is reasonably quiet, not really audible from inside the house. Our oil fired boiler was far louder, and you could easily hear it, so I’d say it’s an improvement on the noise front.
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I’ve not much to add, except to say good insulation is essential; however if you have a wood fired stove then you need a certain amount of air flow to ensure efficient combustion. Also, I have underfloor heating that some believe make the system more effective.
My first ASHP lasted 10 years; its replacement is much more efficient. The water temperature is higher, which means that an immersion heater is needed to raise storage temperatures to eliminate legionella bacteria. It is also quieter than the old model.
I changed installer, who happened to be half the price of the previous one, and he had a better service rating from Vaillant.
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I guess balanced flue boilers create a rushing sound when on… but only for short periods. They heard the heat pump more regularly and constantly, kind of sounding like a large freezer compressor… which was noticeable in the dead of night. Anyway they have an acoustic baffle now around it and all seems to be better.
However I do hear my neighbours heatpump if walking back up the lane approaching the house in the still of night and that has an acoustic baffle around it. But their heat pump is about 5 years old, I am sure things have improved since then.
As I understand it, these are basically air conditioning systems in reverse, and so there are millions all over the world in use. I would question whether many changes have occurred in the underlying technology. Certainly the electronic management would have improved, along with various sensors and remote controls.
I read efficiency, heat temperature outputs are areas that are improved including by using improved coolants etc…
As far as noise, the web seems to include far more references to noise than when I last looked… and even growing numbers of specialist companies providing ASHP acoustic mitigations such as
Why an Acoustic Enclosure is Essential for Your Air Source Heat Pump: A Comprehensive Guide - Ikoustic Soundproofing.
I wasn’t aware of the BS4142 noise pollution tests (these take into account your ambient noise levels which are far lower in the country) that the council will undertake if there is a complaint of noise from neighbour over an ASHP… it looks to be a bit of an area that is developing perhaps noise levels haven’t significantly reduced.
I think when I eventually get around to it, I will defo be using a proper acoustic enclosure.
The day’s off opening a window to see if the heat pump is on, by hearing it are long gone, if you have the right unit.
The cheaper unit’s are normally old design unit’s, cheap but really, they are crap compared to the new unit’s you can get.
I only install Mitsubishi ecodan, and the new whisper quite range, are just that. You need to virtually look to see if the fan blades are moving to know it’s on.
Also you will or should get all the calculations on heat loss, epc, room calculations, running cost predictions, etc. Before you start the installation.
Also a heat pump should never be installed if these calculations don’t work. Plus the installation needs to be signed off, so any problems going forward, be it the design performance or how it’s been installed is traceable if needed. As they can be made to put it right at their own expense if found to be lacking.
That’s why it’s important to do it right, plus help you get your £7500 grant pay back.
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The Mitsubishi whisper quiet models certainly look better, with 45 dB (A). That level is akin to background talking or background radio in a living space environment. So relatively quiet but above the threshold of distracting somebody concentrating or trying to get to sleep. So even those look like they require considered placement or acoustic enclosures… depending on ambient noise levels, but should be easier to manage.
dB (A) reference chart
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As with all heatpumps they need the correct positioning and not just for noise.
But the ecodan is certainly the quietest i have come across. Plus the noise quoted is the maximum, and most off the time it wouldn’t be anywhere near this as they dont run at maximum all the time. It’s only really if you had used a lot of hot water in one go that you can get them working flat out for about 30 minutes or if starting from cold.
Ticking over they hardly make a sound, i know as i fit them and have been doing so for about 15 years or more
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Out of interest have you much experience with the new ASHP models that produce 70 to 80 degree Celsius temperatures using the R290 coolant? If so any views?
These to me look like they could be a game changer, and less damaging to the environment if there is a leakage.
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No much yet.
The propane is interesting, but as far as the high temp goes not much on them yet to go with.
As the tests done the units didn’t really go that high in temp whilst being used
It also depends on who or what you read as to if you believe the findings or not.
But the technology will certainly move forward fast on these, they have already moved away from the twin compressor to a single unit like the low temp heatpumps have to help make more efficient.
But the efficiency is still obviously less.
But really we should be looking at more heat efficient homes rather than more heat.
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Ours is an ecodan unit. One of the reasons we went for the ecodan is worries about disturbing our neighbour who’s house wall is just a few metres from the unit. I don’t think its one of their quietist, its a 14kw double fan unit. As you say most of the time it is very quiet, even when its running a hot water cycle its pretty quiet. It’s only when it gets to sub zero outside, when its having to work hard, that it gets to that conversation ‘noise level’ of noise… and its a fan noise rather than someone speaking type noise… The neighbours say they haven’t noticed any noise at all.
When we had one, the external unit was indistinguishable from a large AC unit both visually and from a noise perspective. Effectively being the same thing in reverse.
In some parts of the world, such things are commonly just outside windows (placement options on small balconies being limited) and the noise was not loud but definitely noticeable.
Noise mitigation is probably less of a concern than hiding the unit but there are specialist products on the market for enclosing both ASHP and AC units in wood and meta trellis of various designs. Way back when, our neighbour hid theirs by growing blueberries on a trellis from the garden centre. Although outside units are unsightly, there are countless creative ways to hide them without impeding air flow.
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Yes looking into it further, it appears the real issue is potential night disturbance where people have bedroom windows slightly open at night, if units are not kept away from bedroom windows (and building regs in the UK have some limits here anyway) then it can cause sleep disturbance which contravenes WHO guidelines. Building regs also stipulate where they (and air conditioning coolers) can be placed so as not to affect too significantly the visual amenity too.
I suspect in the UK it is more about noise than visual impact… but some newer more efficient designs do appear significantly less noisy than earlier models. Models that peak noise output less than 45 dB(A) should be easier to mitigate and/or manage.
As I say my daughter did notice the noise from their ASHP at night, despite theirs following the building regs, as it was a newly built house… hence why they put an acoustic enclosure around it… I believe problem solved now.
It’s currently on our todo list for the giant AC units we have here. Mounted well away from any windows and round the back of the house out of site… but facing directly towards the rear neighbour’s living room. While such things are not considered unneighbourly here, I certainly notice it and want to avoid ruining their view. Regs here stipulate that such barriers must have a submerged concrete foundation (don’t want them flying away hitting people in a storm) so they might have to put up with a sunflower gate for 1-2 years while funds accumulate for a better solution.