Air Source Heat Pumps

c13pep

Hi
I have an ASHP feeding 20+ radiators and can categorically state that it works even with our target lounge temperature of 24 degrees. I have posted on here before that we operate the system as we did our previous Calor boiler ie. shut down between 10.00pm to 5.30am. My costs are acceptable for my large house and much in line with what I expected now that we are all electric.
I fitted solar panels purely as a way of generating my own electric with the added bonus of a government payment every quarter.
The one thing I learned early on is that these systems are especially suitable for underfloor heating where lower temperatures give out a more uniform heat but for us this was not an option.
Our maintenance engineer recently told us of a latest development where flow temperatures are 60+ degrees but the system is still quite expensive.
If you can`t get mains gas then I would have no hesitation in recommending ASHPs
CHRIS

lovehols

Thanks Chris

We are still researching options. We have read about Grants doing a hybrid system oil and ASHP but we have read so many mixed opinions.

c13pep

My own system was originally a hybrid system retaining the calor boiler for backup during very cold spells, however the second boiler has never been activated (outside temperature sensor kicks in at minus 5-8 degrees). As mentioned my system is shut down overnight when temperatures are at their lowest so it doesn`t operate when it would be at its least efficient. It does not take long for the system to warm the house thro`
One thing I would do differently, in hindsight, would be the installation of solar hot water to give even more savings.
If your installing underfloor heating then I would go for the ASHP as I can`t see any reason not to.
PS my system is now 4 years old
CHRIS

lovehols

c13pep wrote: »

My own system was originally a hybrid system retaining the calor boiler for backup during very cold spells, however the second boiler has never been activated (outside temperature sensor kicks in at minus 5-8 degrees). As mentioned my system is shut down overnight when temperatures are at their lowest so it doesn`t operate when it would be at its least efficient. It does not take long for the system to warm the house thro`
One thing I would do differently, in hindsight, would be the installation of solar hot water to give even more savings.
If your installing underfloor heating then I would go for the ASHP as I can`t see any reason not to.
PS my system is now 4 years old
CHRIS

I guess one of my issues here is you say "the system is shut down when it would be at its least efficient". I guess that's my argument :rotfl: I want a system that is efficient when temperatures are low! For me that's when I want a toasty warm house and a nice steamy bath!!

matelodave

Your main problem with people's opinions is more often than not it's those who are dissatified who complain and criticise. There are probably many thousands more who are quite happy.

As has been said, the main thing is to make sure that the system is designed as a whole by someone who understands what they are doing and for you to also understand how it works and to make sure that the whole system is specified correctly.

Getting several quotes should produce similarly specified systems - if not then you should understand why and what the differences are.

I prepared accurate information regarding temperatures required, room sizes together with wall, floor, roof and window construction info so they all had the same info to work from. I also did my own calculations to get a rough idea of what was required.

I asked six companies to quote - two wanted a big lump of money up front, one didn't reply and three gave me a quotation, two based on Ecodan and one on Daikin or Ecodan.

I visited two of the companies to see the equipment in operation and both of them visited my house as well. In the end I selected the Daikin solution with a PolyPipe overlay underfloor heating system as the quote was quite competitive and the company demonstrated significantly more knowledge. This was over seven years and eight winters ago and I'm extremely happy with it all.

There's no problem with having steamy baths, you just have to accept that you might need to use an immersion heater to raise the water temperature to the higher level - using E7 would help with that.

We are more than happy with our hot water at 45 degrees but if I want it hotter than 50 then the immersion heater will kick in (as it does every Saturday to sterilise the tank at 60 degrees). The extra 10 degrees on E7 wont cost much more as you've had the benefit of the heatpump efficiency to get it most of the way. You could also run it all night on E7 (or E10) if you so wish.

Likewise you can have the house as hot as you like, you just need to ensure that the ASHP has enough capacity and that the radiators/heat emitters/underfloor heating is correctly sized to suit the flow temperature as well. The programmable stats turn it down to 17 degrees overnight and back up during the day.

Each room has it's own programmable thermostat and the temperature is adjusted according to it's use - ie we dont have the bedrooms at 20 degrees all day, just for an hour or so in the mornings and at bedtime. We reduce it to 15 overnight as we cannot sleep in a hot room, likewise the bathroom only needs to be around 20 in the mornings and evenings and is set to 17 during the day. The study & lounge are set to 20 but the study goes down to 17 in the evening when it's not in use. Underfloor heating keeps all room toasty warm all over - no hot or cold spots and a real treat underfoot in the bathroom

Most problems occur when the either the heatpump is undersized or the rads etc are too small to heat the rooms at the lower flow temperatures, usually because the heatpump has been bunged onto an existing system.

You last comment indicates that you dont really understand how they work - we dont shut ours down overnight, just reduce the temperature. We cant sleep in a house that's much above 15-16 degrees, reducing the temperature a bit improves the system efficiency - even at 0 degrees outside, the system has a COP of over 2. With decent insulation the house may not need heating at all overnight.

lovehols

Thanks for that. You've given me a lot to think about. It's definitely one of my top priorities in the redesign and extension of the bungalow, it must be warm. I'm always cold!

c13pep

Your extension will be built to current building regulations, however these need to be considered as the minimum with regard to insulation etc. In the final analysis it will all come down to cost which climbs disproportionately the more you install heat retaining solutions.
My ASHP was installed retrospectively on to an existing radiator system by a fully competent installation team consisting of plumbers, refrigeration/air con engineer and a fully trained Mitsubishi heat pump engineer. Even so the set up procedure took three months to perfect to our situation. I have to say that the technicalities of the system were really of no concern to me only the promise that it would work to my satisfaction.
Your research will have shown that it`s the installation that counts with most of the current day equipment being fairly equal. All of the failures reported on the various forums are almost always down to poor setting up of the system and/or poor initial calculations.
Good luck with your project
CHRIS

richardc1983

c13pep wrote: »

Hi
I have an ASHP feeding 20+ radiators and can categorically state that it works even with our target lounge temperature of 24 degrees. I have posted on here before that we operate the system as we did our previous Calor boiler ie. shut down between 10.00pm to 5.30am. My costs are acceptable for my large house and much in line with what I expected now that we are all electric.
I fitted solar panels purely as a way of generating my own electric with the added bonus of a government payment every quarter.
The one thing I learned early on is that these systems are especially suitable for underfloor heating where lower temperatures give out a more uniform heat but for us this was not an option.
Our maintenance engineer recently told us of a latest development where flow temperatures are 60+ degrees but the system is still quite expensive.
If you can`t get mains gas then I would have no hesitation in recommending ASHPs
CHRIS

When you say you shut it down do you mean a night set back to a lower temperature? You will likely find it saves more if it doesn't have to work as hard the next day to get back up to comfort temperature.

Cardew

c13pep wrote: »

Your extension will be built to current building regulations, however these need to be considered as the minimum with regard to insulation etc. In the final analysis it will all come down to cost which climbs disproportionately the more you install heat retaining solutions.
My ASHP was installed retrospectively on to an existing radiator system by a fully competent installation team consisting of plumbers, refrigeration/air con engineer and a fully trained Mitsubishi heat pump engineer. Even so the set up procedure took three months to perfect to our situation. I have to say that the technicalities of the system were really of no concern to me only the promise that it would work to my satisfaction.
Your research will have shown that it`s the installation that counts with most of the current day equipment being fairly equal. All of the failures reported on the various forums are almost always down to poor setting up of the system and/or poor initial calculations.
Good luck with your project
CHRIS

Agree completely.

For such an expensive and complicated heating system Mitsubishi(for the Ecodan) should have their own factory installers and give the system their full guarantee of performance.

c13pep

Shut down is exactly that, system is switched off for night, which then makes my insulation etc. earn its keep. Even in weather like today (beast from the east) my house does retain its heat well.
CHRIS