UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

albyota

borderfox, drop me a PM if you need more info, I have the mitsubishi Ecodan system.

peat

I have a wet electric heating system which consists of a 250 litre thermal store directly connected to radiators and a 12 kw heatrae sadia boiler which is programmed to heat during off-peak periods of the Hydro-electric economy 10 tariff. DHW is direct from the mains through a coil within the thermal store giving mains pressure hot water. The thermal store is also directly connected to a back boiler in an open fire (the fire is seldom used).
Would it be possible to connect an air to water air source heat pump to the system and would this be efficient?
I was thinking that an ASHP could heat the water in the return to the thermal store which could be boosted by the heatrae boiler, but I'm no expert.
Given the potential payments from the Rewnewable Heat Incentive it would appear to be economically viable even if potential savings were marginal.

albyota

peat, the set up you have, with radiators (how many?, what size?, size of rooms?) yes, you most certainly can connect an ASHP to it, but should probably consider the Sanyo CO2 system on its own, without the tank, i.e just with controller, this heats water to 65 degrees, connect this to the existing flow / return pipes, you will not need the 12 kW electric element much at all, however, you will need to run this at the times you get the cheap rate leccy, therefore you would be getting your 12 kW output from approx 3.6 kW of input....much more efficient.

peat

Why without the tank? Surely once the tank has been initially heated there would be no difference. At the moment I find that the heat accumulated in the thermal store is not quite enough to respond to heat demand at times outwith the off peak electricity periods and thus the rads are warm rather than hot. I was thinking that if the water entering the tank (the return) could be heated by the ASHP even at full rate electricity times the requirement for heatig with the conventional boiler would be minimised.

albyota

No, peat what I meant, is the Sanyo system normally comes with its own tank, but you can use it on its own with a third party tank like the Heatrae Sadia you already have, but to do this, you need their third party controller. if you don't use the back boiler very much.... either disconnect it or valve it out of the circuit, as it is dumping heat straight up the chimney!!! as for when it is operating, if you run it at peak times, it will cost more to run unless you change your E10 tariff to normal.

timstopp

Hi, my old 50,000 btu warm air heater has died and need replacing. I wondered if any one knows if it is possible to get an air source heatpump that will replace it ie to heat air to air rather than air to water. This would be a great system as my house is fully ducted, and I could I suppose benefit from cooling in the summer months. The ducting, boiler and water pipes etc are all housed in a central column in the house. So any heat exchanger would need to be at least 6 ft from an outside wall.
Having looked on the internet, no one seems to give prices for any of this equipment, to replace my warm air gas boiler is going to be £3000, so am I in even the same ball park for alternative heating?

rhubarbe

I'm up for an ASHP. We're scrapping a 20 year old LPG combi boiler (we have no mains gas) having just costed our heating/DHW at £1 an hour and another price rise to accept if we want to order any more LPG (we don't).

There being just two of us living in a small detached bungalow, we have two electric showers that we are not planning to replace; we don't take baths though we do wash and we need DHW for washing up, etc.

Having got used to the instant heat from a combi I don't much want a tank to store water: I haven't got the room and we just don't use enough to justify the standing losses.

Does anybody have any suggestions as to how we could use the ASHP - I'm going for an Ecodan - for space heating (radiators), and some other, tankless method for DHW?

I have done loads of research on unvented tanks by all manufacturers, and yes, we could take a small tank if we had to but I'd really prefer not to if there is an instant source I could use instead.

Swipe

The ecodan does dhw in the same tank housing as the CH water. Seems pointless looking for instant alternatives when a DHW tank is included.

arty68

Swipe wrote: »

The ecodan does dhw in the same tank housing as the CH water. Seems pointless looking for instant alternatives when a DHW tank is included.

The Ecodan usually comes with a tank (you can buy it without the tank)just for the DHW the CH is fed directly from the Heat pump.This is one of the reasons I didn't choose an ecodan as you have no backup for your heating.

You could just get the ecodan or any other ASHP for your heating and either keep your combi just for hot water or replace your combi with a newer LPG combi or electric boiler.

There are combi like ASHP available in Japan which will be over here sometime in the future so you could wait.

Are you changing your rads because they will need to be oversized if you want good efficiency?

thills

You can get some pretty good undersink instant heaters for water, if your determined to keep the electric showers, have fitted some in the past & they work well if you accept a slower fill rate