Air Source Heat Pumps

waltsalt

TiredGeek wrote: »

I always doubt a recommendation of a company given over an open forum, smacks of advertising to me.....

By a new member with only 2 posts, both of which are promoting the same company no less.

richardc1983

Ive got an LG split system I wrote the https://forums.moneysavingexpert.com/discussion/1464827 topic which is a sticky. Whilst I know that Air to Air systems are good for heating if no gas supply is available I am undecided if mine is better than using the GCH I also have installed. System was mainly installed for cooling in the summer due to me working nights & living next to the motorway I cannot sleep with windows open due to the noise.

I wondered if I could get your advice, my 2 bed end terrace house has both GCH and Air to Air heat pump or air con as many know it. I have found that it is cheaper to heat the house with gas and more comfortable particularly for the lounge as the radiator is under the window. In the lounge is a door that leads to the kitchen and a door that leads to the entrance hall and stairs. In the kitchen, lounge and bedrooms there is a air conditioning unit connected to the outdoor unit so in total 4 units. I find that the hall and stairs and bathroom don't keep warm if I am using the air to air system unless I leave internal doors open which I don't mind doing as I like heat to circulate to the upstairs. Last year I tried turning off all radiators except the hall and bathroom and running the boiler on low and timed when the air to air system was running so those areas received heating.

Having the GCH on the whole house is lovely and warm with a flow temp of 40-45C. Whilst the air to air system warms the house up very quickly if cold I find its more expensive to keep rooms at set temps and because the units cycle in and off when the temperature is reached you have to have a higher set point as when the units are in the off cycle there is no background heat.

Have you any advice and do you think it is cheaper to use the air to air system or GSH. I fitted wired timer controllers to each room for the air con systems so I could have them all on independent timers. I found that to keep the house warm on those really cold days last year I was using approx £4 of electricity, that was to heat the house all day upto bed time at night. I work nights also so when I have my days off I am in during the day. I am just not sure which to use.

I prefer warm air but I think comfort is better from the radiator system. I have also found that I can keep the house currently an even temp by having the thermostat set at 19C in the hall and the doors open so the rooms maintain about 19/20C the boiler is set at 40C flow temp and the heating on constant. Some evenings I put the thermostat up to 20C when its a bit chillier outside. I don't like to have the boiler set to a high flow temp as I don't like walking into a room where it feels stifling from the heat coming from the radiators due to the flow temp being so high I like a comfortable well maintained temp. So having the boiler set lower whilst longer run times with the pump circulating the burner itself isn't running for that long as it only fires at a low temp.

I find I have to have the set points on the air to air system at approx 21/22C but I worry that as I use this system for cooling in the summer it puts more wear and tear on it using it for heating in the summer which as we know these systems work harder in heating than they do in cooling. In cooling the compressor can hardly be heard as it just ticks away.

When I bought the house I had the boiler fail within 3 months and a new fan was required along with other parts. Gloworm attended and said the reason that these parts fail is because people run them on max output all the time such as heating flow temp set to 80C and hot water set to max. This puts more stress on the components rather than running at a lower temp and for longer periods.

I just cannot decide which to use. I know Cardew you run your GCH on max to get upto temp quickly. Jeepjunkie you have an Air to water system and fan coils.

Any advice or discussion welcomed.

albyota

Hi Richardc1983,

Even with a COP of 3 the GCH will be cheaper

Some links for fuel prices

http://www.nottenergy.com/energy_cost_comparison
http://www.energysavingtrust.org.uk/Energy-Saving-Trust/Our-calculations

You would be better off using the gas central heating, and only use the aircon for cooling, however, there may be times say in autumn and spring when the air con is more convenient for heating just a couple of rooms rather than pfaffing around with radiator valves / TRV's.

AL

Cardew

Richard,

As usual you have carried out a comprehensive appraisal of your two systems, and really there is little more to add, as it is down to personal choice. I wouldn't think there is too much difference in running costs between an Air to Air ASHP and gas CH during the milder days in winter.

The Air to Air ASHP I have in the USA was installed during construction and is ducted to each room. I personally wouldn't like your solution of having to open doors to allow heat to circulate. Also the big advantage of radiator heating is that you can just heat one room if required.

When I bought the house I had the boiler fail within 3 months and a new fan was required along with other parts. Gloworm attended and said the reason that these parts fail is because people run them on max output all the time such as heating flow temp set to 80C and hot water set to max. This puts more stress on the components rather than running at a lower temp and for longer periods.

I find the above hard to believe, and suspect it is simply the(mistaken) opinion of the fitter who attended. I doubt if a letter to the technical department at Gloworm would elicit the same response!

hebridean

I'm currently on an economy 10 tariff with the Scottish Hydro and the peak/off peak units are working out about the same. I run the ashp at this time of the year during the cheap rate times and will run it all the time when the weather turns colder.
Yesterday i tried getting quotes for the economy 10 rate and found it wasn't possible online and phoned a couple of companies, E.ON and EDF. Both were cheaper than the Hydro and i would save about £150 on the year if i changed. However if i add up my peak and off peak units and use this total i have found that i could save another £100, but i would have to change the meter etc.
So how are you good people on this forum running your ashp's by way of electrical supply?

Many thanks

Cardew

Many companies will not cater for an Economy 10 meter and of course the comparison websites as well.

I believe prevailing wisdom is that running an ASHP on Economy 7 only makes sense if your system has a large thermal store(a big tank of water) that the ASHP can heat overnight.

Alfie1939

My son has installed the under floor heating pipes and manifold and wants to use a big tank heated by economy 7 and topped up with day tariff.
What does he need to complete the installation please?
Alfie

zeupater

albyota wrote: »

... however, there may be times say in autumn and spring when the air con is more convenient for heating just a couple of rooms rather than pfaffing around with radiator valves / TRV's ...

Hi albyota

We're currently considering a top-end air/air HP which has a claimed COP of ~4 to 5+ (depending on unit size) for a single unit and using it mainly for heating in the shoulder months when there's still the likelihood of spare pv generation. The range we're considering has an eco-mode which seems to restrict the load to 75% or 50% of nominal performance, which helps match output to generation ....

Haven't jumped yet as when I wrote 'we', I meant 'me' ... MrsZ is on-board with the idea, but still wants to see a range of different units for 'aesthetic comparison', which probably means that whatever we end up with needs to match the curtains! .. :D

HTH
Z

albyota

Hi Ze, I know you have considered the LG Artcool and Mirror units, these are probably the better looking units, for standard wall mounted units. For quality, I would put Mitsubishi first, Panasonic second followed by Fujitsu then Daikin. although I would prefer to build a ducted unit into a bulkhead ceiling.

zeupater

albyota wrote: »

Hi Ze, I know you have considered the LG Artcool and Mirror units, these are probably the better looking units, for standard wall mounted units. For quality, I would put Mitsubishi first, Panasonic second followed by Fujitsu then Daikin. although I would prefer to build a ducted unit into a bulkhead ceiling.

Hi

I like the features on the Panasonic units, but current thinking is the Daiseikai 6.5 range because of the very low minimum power draw & wide performance range. The eco setting, according to the manufacturer specs, allows for manually limiting the performance which would be useful in overcast conditions. It's probably the combination of the performance & eco function which particularly attract me, but they are pretty expensive units compared to something like the LG units which you mention above (which are also MrsZ's current favourite) ....

I've checked the specs of a number of the manufacturers & haven't found a unit which has the ability to restrict the power drawn ... do you know of anything other than the SD6.5 which has this ability? ....

It's probably academic at the moment as we're probably too deep into October for it to make a difference at the moment, so it looks like a late winter decision for an early spring install.

Z