Just wondering if anyone has actual experience of air source heat pumps?
My existing boiler is 26 years old and I'm looking to replace or upgrade. The easy solution is to simply fit a replacement condensing boiler but, as I have solar panels and am also looking at batteries to maximise the solar usage and cheap overnight prices, it makes sense to consider heat pumps.
I've had a survey done, results awaited.
So, if anyone has actual experience, I'd like to hear from you. In particular, how it works during the summer for hot water only.
No experience, but from what I have read and seen, there is a lot extra to do to convert to a heat-pump:
1) you need to change to much more powerful radiators (larger or more panels/fins) as the water flow temperature is much lower or you'll have to retrofit under-floor heating.
2) because of the lower water temperatures, you may need to replace pipework and the pump to achieve high enough flows.
3) if you haven't already got it, you'll need better insulation/windows, as the lower flow temperature is more suited to semi-continuous temperature maintenance, rather than rapidly raising temperatures and then turning off a few times a day.
My own (gas) system was sized using an 80°C flow temperature, as recommended at the time. However, I have been gradually replacing radiators and some piping, as rooms are redecorated and currently run it at 67 to 70°C and when further work is done, I should be able to drop it to 50 to 55°C. It is therefore likely to be almost heat-pump ready for the future.
@stevewalker (https://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=5329) thank you but that is why I'm asking for actual experience. I've been watching far too many YouTube videos but the Heat Geek (IMHO) makes a lot of sense.
It seems to really require a change in mindset in how you heat your home. "Low and slow" seems to be the Mantra but it also works for modern boilers.
Having had a survey, the thinking is that my pipework is OK, the radiators may be OK (Sums awaited) but the consultant also said it might be worth cascading the downstairs (Doubles) rads upstairs (Singles) and get new rads downstairs as you don't want the bedrooms to be so warm.
Our house built 12 years ago has a heating system based on a air-heat pump, extracting energy from the air to heat the water.
- we have a big hot-water-tank heated with this energy. It's big as it then has to deliver hot water and energy to drive our forced air heating and our floor heating pipes.
- the max target heat in the tank can be configured up to 100°Celsius. Recommended is max 70because of the lime deposits (but then you need to heat to 90 at least once a week to eliminate legionnaires fever.
- we also have electric heating rods integrated, in case the outside temperature drops below the critical values (iirc below minus 20 or 30). Below those temperatures the heat pump cannot extract energy from the air.
- we have bought an inverter option which allows the forced air heating to deliver cooled air in summer (even thoufh it's only about 2°cooler... it makes a difference)
I hope I got most of the terminology right. It's a vocabulary not often used...
@AlexanderJesse (https://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=6316) is the system also twelve years old? How do you find the running costs? Regarding legionella, I believe the system only needs to reach sixty degrees to eleiminate it.
I have a number of clients who have tried air source heat pumps, some had them foisted on them by developers, some chose them.
The feedback I have heard is they are not nearly as good as the salesman tells you. They work best in modern, last ten years, constructed homes with high levels of insulation, high grade triple glazing and under floor heating.
You WILL need TRIPLE radiators, extra radiators, underfloor heating and an extra jumper, or two. Apparently a lot of the issue is the British climate. It is not particularly suited to air source heat pumps.
Of the half dozen clients that have them, two have retro fitted 50% more rads since the pump was installed, one has dumped the pump and gone ground sourced, which is significantly more expensive, but significantly better, one is moving house because it's cheaper than sorting it out and the other two have installed more solar panels, batteries and are going for full on electric boilers.
When it comes to consultants/salesmen, caveat emptor. Don't forget, they are not your best mate, they're getting paid to shift them.
Try to actually speak to people who have them installed rather than the guy trying to flog them to you.
Quote from: emjaybee on November 06, 2022, 06:47:41 PM
Try to actually speak to people who have them installed rather than the guy trying to flog them to you.
That's why I'm asking :D
Yes the heating system was installed as part of the houae construction. So 12 years running.
So far no major problems. Had to call service once because of some leakage in the primary heat exchanger (air fro the heatpump to water) a 2 hour job including some soldered copper tube.
Lime deposits might be a problem if the hot water tank has no service opening through which a mechanical cleanung of the deposits can be done as in our case. We did one chemical cleaning after 10 years and to our joy (having high level in our water!) had no deposits. According to the mechanic doing the cleaning a sign of a high quality steel used for the tank.
Reasoning for the legionella buggers: if you keep the temperature ALWAYS above the 65/70° , these temeratures might suffice. But as the control logic will kick in heating only if the tank water temperature is below 40, we were told to execute the heat treatment once a wèek with the higher temps (alas programmed....). Just to be sure.
The position of the heat pump can cause discussions with neighbours. So
A) choose a "not too loud init"
B) plan the position well
These vents can cause quite a wind force :D
Some hot water tanks allow for multiple heat sources. One could be the air pump, one could hot water solar units,...
@AlexanderJesse (https://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=6316) thanks.
I've got a location planned in a corner which is always warm, away from the neighbour and away from our patio. The modern pumps are very quiet although I'm unsure if they stay quiet over the years.
Does it run all day during the summer when its only supplying hot water?
Quote from: GrahamB on November 06, 2022, 07:06:52 PM
@AlexanderJesse (https://www.ngaugeforum.co.uk/SMFN/index.php?action=profile;u=6316) thanks.
I've got a location planned in a corner which is always warm, away from the neighbour and away from our patio. The modern pumps are very quiet although I'm unsure if they stay quiet over the years.
Does it run all day during the summer when its only supplying hot water?
Even in winter it does not run continouously!
Only when the energy stored in the hot water tank gets low
If low temps outside are frequent ( as they are here in the swiss alps, maybe part of the british isles are warmer in winter due to the gulf stream ) the heat exvhange radiator needs a defrost option which means that hot water from the tank is used to deice the heat pump outside