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

Pincher

To albyota,

Thanks for the fast response. I did have a look at the ESP Ecocent, which you mentioned in an earlier post in this thread. It is actually pretty close to what I want. To ensure continued cooling operation, I can manually dump the hot water one way or another: tell everyone to have lots of showers:D.

The two big ducts gave me a sinking feeling. I have just redecorated an upstairs landing ceiling, specifically to arrange ducting access from the loft into the hot water cylinder room (2m x 1.3m, not closet or cupboard, but with sloping ceiling,). The positioning of the duct access is identical to the Ecocent picture relative to the existing cylinder! I had boxed in the space between two rafters (about 200mm wide), so that it is enough for ONE insulated duct. It was plastered, ceiling papered and painted, LAST WEEK! This was meant for the heat recovery extract duct, branching off to the en-suite and the second bathroom, which are on either side of the cylinder room. If I put in the Ecocent, I will need three rafter gaps, and have to rip out the ceiling, again.

I was hoping there might be a heat pump unit that I could install in the loft, INLINE with the fresh air output from the heat recovery unit. The heat will then be dumped in the cylinder via flexible hoses through the aformentioned loft access gap.

The Ecocent is very promising, because the first floor will be underfloor heated, with the manifold in the selfsame cylinder room! We have already plumbed in the flow/return for the manifold from the gas boiler, but if I upgrade to Ecocent in a few years time, the manifold is just 1.5 metres away. The cylinder room is plumbing central, and the Ecocent can replace the existing cylinder.

The current plan is to install the heat recovery unit in the loft for now.
When there's a suitable cooling heat pump, that will be slotted in inline as I described. Heating in winter would be useful as a backup to the gas central heating. For this to work, the Ecocent needs to have an immersion element, as the gas boiler would be broken in this scenario.

If you look at a generic dual action (cooling/heating) heat pump, you have one flow/return on one side, and another flow/return on the other side. I just want the right hand side to be an enclosed refrigerant to air heat exchanger, packaged as an inline module with in and out duct connectors. The left hand side are flow and return pipes to the cylinder. Essentially, it's a repackaged outside unit used in reverse mode.

richardc1983

Pincher wrote: »

To albyota,

Thanks for the fast response. I did have a look at the ESP Ecocent, which you mentioned in an earlier post in this thread. It is actually pretty close to what I want. To ensure continued cooling operation, I can manually dump the hot water one way or another: tell everyone to have lots of showers:D.

The two big ducts gave me a sinking feeling. I have just redecorated an upstairs landing ceiling, specifically to arrange ducting access from the loft into the hot water cylinder room (2m x 1.3m, not closet or cupboard, but with sloping ceiling,). The positioning of the duct access is identical to the Ecocent picture relative to the existing cylinder! I had boxed in the space between two rafters (about 200mm wide), so that it is enough for ONE insulated duct. It was plastered, ceiling papered and painted, LAST WEEK! This was meant for the heat recovery extract duct, branching off to the en-suite and the second bathroom, which are on either side of the cylinder room. If I put in the Ecocent, I will need three rafter gaps, and have to rip out the ceiling, again.

I was hoping there might be a heat pump unit that I could install in the loft, INLINE with the fresh air output from the heat recovery unit. The heat will then be dumped in the cylinder via flexible hoses through the aformentioned loft access gap.

The Ecocent is very promising, because the first floor will be underfloor heated, with the manifold in the selfsame cylinder room! We have already plumbed in the flow/return for the manifold from the gas boiler, but if I upgrade to Ecocent in a few years time, the manifold is just 1.5 metres away. The cylinder room is plumbing central, and the Ecocent can replace the existing cylinder.

The current plan is to install the heat recovery unit in the loft for now.
When there's a suitable cooling heat pump, that will be slotted in inline as I described. Heating in winter would be useful as a backup to the gas central heating. For this to work, the Ecocent needs to have an immersion element, as the gas boiler would be broken in this scenario.

If you look at a generic dual action (cooling/heating) heat pump, you have one flow/return on one side, and another flow/return on the other side. I just want the right hand side to be an enclosed refrigerant to air heat exchanger, packaged as an inline module with in and out duct connectors. The left hand side are flow and return pipes to the cylinder. Essentially, it's a repackaged outside unit used in reverse mode.

If you was to go with the Ecocent it doesnt give very impressive figures.

http://www.esavep.com/products/domestic-hot-water

Scroll down to the following graph:

Different performance under different conditions
For model: Ecocent (DHW unit) Air Temperature °C
Outlet hot water temp °C
4555
45.0 55.0 QH NHQH
NH COP COP -2 1.2 0.75 0.9 0.84 1.60 1.07 2 1.7 0.77 1.4 0.86 2.21 1.63 6 2.1 0.785 1.8 0.875 2.68 2.06 10 2.4 0.8 2.1 0.89 3.00 2.36 15 2.6 0.81 2.3 0.9 3.21 2.56 18 2.75 0.83 2.48 0.93 3.31 2.67 22 2.93 0.85 2.68 0.97 3.45 2.76 26 3.15 0.875 2.92 1.015 3.60 2.88 30 3.43 0.9 3.21 1.06 3.81 3.03 34 3.75 0.93 3.53 1.09 4.03 3.24 38 4.1 0.962 3.9 1.112
4.26 3.51 43 4.49 0.997 4.29 1.117 4.50 3.84
Different performance under different conditions

Performance is terrible at 6C relatively mild for uk winters!

I will reccomend again if you go to

http://www.refrigeration-engineer.com/forums/forumdisplay.php?f=78

Ask there the same question you have posted here, the forum is full of engineers who do this kind of thing day in day out and will gain more views than on here where only a handful of engineers are based.

Pincher

richardc1983 wrote: »

If you was to go with the Ecocent it doesnt give very impressive figures.

http://www.esavep.com/products/domestic-hot-water


I will reccomend again if you go to

http://www.refrigeration-engineer.com/forums/forumdisplay.php?f=78

Ask there the same question you have posted here, the forum is full of engineers who do this kind of thing day in day out and will gain more views than on here where only a handful of engineers are based.

It's just a heat pump with two heat exchangers. A refrigeration room in a butcher's shop is probably more complicated. I appreciate that a refrigeration engineer can knock one together in a day, but that's a custom job. I would lke to see Mitsubishi, Glow worm etc. who do heat recovery units to do an optional add-on. The flow/return could go straight up through the roof, and be connected to a fanned radiator, if you don't want to heat water with it.

Here is a combined heat source/heat sink solar panel idea. The top side is a regular solar panel, and the underside is a radiator. Two flow/return pairs go from this panel into the solar pump (more of a heat transfer station now) The solar pump is also connected to the cooling/heating heat pump in the loft, as well as the cylinder. The heat flow is managed so that heat is only wasted when nothing needs it. Note that this arrangement means the heat pump need never stop to defrost. If the external radiator freezes, we circulate heat from the thermal store to the heat pump, as well as to the radiator to defrost it. The property of the circulating fluid is probably different for solar collection and heat pump, so extra heat exchangers and pumps may be required.

I think I'll send this suggestion to Mitsubishi.

egyptiangirl

Thanks to you guys who have posted on this. As I posted elsewhere I'm considering this option however I think you are def experts and I am rather lost now!

A really stupid question then, that was kind of hinted at...

So with this system, can you use 'normal' radiators?

rhubarbe

I certainly hope so. Mine is about an hour away from being finished....

richardc1983

egyptiangirl wrote: »

Thanks to you guys who have posted on this. As I posted elsewhere I'm considering this option however I think you are def experts and I am rather lost now!

A really stupid question then, that was kind of hinted at...

So with this system, can you use 'normal' radiators?

Yes you can but you may have to replace some radiators and oversize them as you have lower flow temps.

Cardew

egyptiangirl wrote: »

Thanks to you guys who have posted on this. As I posted elsewhere I'm considering this option however I think you are def experts and I am rather lost now!

A really stupid question then, that was kind of hinted at...

So with this system, can you use 'normal' radiators?

Not a stupid question at all.

There are two types of Air Source Heat Pump(ASHP)

In simple terms, one blows hot air and the other provides hot(warm) water to radiators and to a hot water tank - the Mitsubishi Ecodan is the oft quoted example of the latter system.

The problem when adapting ASHPs to existing CH systems is that they are more efficient when producing low temperature hot water for radiators and a hot water tank. They work best with water at around 40C where a gas/oil/lpg boiler will produce water at up to 80+C.

It is obvious that a 'conventional' CH system will have radiators in each room that are 'sized' for water that can be up to 80+C. These radiators will not be big enough to warm a room when supplied with water from an ASHP at 40C, so larger radiators will be required. Or, particularly in new build properties, underfloor heating is specified.

rhubarbe

My 8.5KW Ecodan install was finished about an hour ago and our 20 year old Myson rads are very nearly as hot as they ever were using our previous LPG combi.

We are warm as toast.

Our Ash not happy bunny...

richardc1983

rhubarbe wrote: »

My 8.5KW Ecodan install was finished about an hour ago and our 20 year old Myson rads are very nearly as hot as they ever were using our previous LPG combi.

We are warm as toast.

Our Ash not happy bunny...

Good to hear you are happy with the system... any chance of you taking some pictures for us to see?

What flow temperature are you using, you need to have a lower flow temp to avoid the backup electrical heater coming on.

Andy_WSM

rhubarbe wrote: »

My 8.5KW Ecodan install was finished about an hour ago and our 20 year old Myson rads are very nearly as hot as they ever were using our previous LPG combi.

We are warm as toast.

Our Ash not happy bunny...

Hi Rhubarbe,

Like Richard, I would also be interested in seeing some pics - If you don't have webspace to post them up then you could email them to me (PM me for email address) and i'll post them up for you.

I'd also be interested in hearing more about the system. Operating temperatures, install cost & running costs going forward.

I have a cheap & cheerful heat pump (Trianco) at the moment, which is doing the job, but I am looking to install a somewhat better system going forward (like the Ecodan).