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  • FIRST POST
    • Parkerr12
    • By Parkerr12 18th May 17, 3:08 PM
    • 1Posts
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    Parkerr12
    Air to water heat pump systems
    • #1
    • 18th May 17, 3:08 PM
    Air to water heat pump systems 18th May 17 at 3:08 PM
    We are looking at changing our heating system currently economy 7 storage heaters which are not very effective, also some radiators run from a woodburner. As we do not have mains gas in our area we are looking at alternatives, specifically heating we can switch on as and when required. Looking at lpg gas, and air to water pumps, there are incentives with potential income from air source heat pumps, we would not be interested in the air to air as too disruptive to install.
    Does anyone have any experience of air to water pump system, I have heard larger radiators are needed ?
Page 1
    • lovesgshp
    • By lovesgshp 18th May 17, 4:24 PM
    • 1,259 Posts
    • 708 Thanks
    lovesgshp
    • #2
    • 18th May 17, 4:24 PM
    • #2
    • 18th May 17, 4:24 PM
    If you are looking at a air/water heat pump, then it is not designed to be switched on and off as needed. There are timers, but, these are meant to just reduce flow temperatures (max about 4C for rads) and not for room temps.
    Not always required to change existing rads, but if you are taking out storage heaters then maybe a good idea in those areas. You could replace the storage units with fan coils, but these can be more expensive than rads.
    As Manuel says in Fawlty Towers: " I Know Nothing"
    • Cardew
    • By Cardew 18th May 17, 4:44 PM
    • 27,026 Posts
    • 13,150 Thanks
    Cardew
    • #3
    • 18th May 17, 4:44 PM
    • #3
    • 18th May 17, 4:44 PM
    Welcome to the forum.

    There are lots of threads on ASHPs on this forum. In particular this thread gives the links to some trials carried out on behalf of the Energy Saving Trust.

    http://forums.moneysavingexpert.com/showthread.php?t=2968958&highlight=should+must+do+ better
    • matelodave
    • By matelodave 20th May 17, 4:38 PM
    • 3,086 Posts
    • 1,817 Thanks
    matelodave
    • #4
    • 20th May 17, 4:38 PM
    • #4
    • 20th May 17, 4:38 PM
    Yes, I've got one and had it for nearly seven years and I'm very happy with it BUT if you are seriously considering one then make sure you know how they work and how to operate them. They do not work like a conventional system and getting it wrong will cost you a lot of money and you'll still be cold.

    They are not suitable to just turn on and off, they work best when gently idling witha flow temperature of around 35 degrees C. For every degree above that it will cost another 2.5% or thereabouts on your leccy bill so you need radiators that are capable of working at low temperatures. Likewise you shouldn't turn it off overnight or during the day, just turn the stats down a couple of degrees as it will take a long time to reheat the place.

    Our system will take a couple of days to get the house up to temperature from stone cold unless I tweak the temperature control.Once set up though we've got nice even heat throughout the bungalow.

    You need to ensure that the whole system is designed properly and not just bung onto the end of the radiators that you've already got. We installed it in conjunction with an overlay underfloor wet system but an alternative is for fan convectors which are quite effective with low flow temperatures.

    I've got some info on my set up if you want to PM me
    Love makes the world go round - beer make it go round even faster
    • bazm
    • By bazm 2nd Oct 17, 8:40 PM
    • 2 Posts
    • 0 Thanks
    bazm
    • #5
    • 2nd Oct 17, 8:40 PM
    • #5
    • 2nd Oct 17, 8:40 PM
    Hi, we are considering replacing our lpg bottle central heating with ASHP. Two questions (looking at Matelodave!);
    I have already replaced all the radiaters (they were all small slimline ones, looked old) with the largest double ones I could fit. Is this ok?
    Secondly, the gubbins that fits inside the house will be in the immersion heater cupboard. Does this make a noise as it will be in our main bedroom?
    Many thanks
    • matelodave
    • By matelodave 2nd Oct 17, 9:45 PM
    • 3,086 Posts
    • 1,817 Thanks
    matelodave
    • #6
    • 2nd Oct 17, 9:45 PM
    • #6
    • 2nd Oct 17, 9:45 PM
    You'd have to do some heat loss calculations to see if your radiators would be large enough bearing in mind the lower flow temperatures. It's also worth looking at your insulation as well to reduce the heat losses.

    You can get heatpumps with all the "gubbins" in the outside unit, they are called monoblocs and the circulating water, which contains antifreeze flows through the outside unit.

    A split system has the compressor unit outside and the refrigerant to water heat exchanger and other stuff inside. Ours is a split and the circulating pump is the same as that in a conventional boiler - not ever so noisy but certainly noticable. I doubt its any noisier than your existing LPG boiler.

    You really would need to get a proper assessment to see if it's viable. Get several quotes though and make sure it all gets explained very thoroughly. You do need to compare system designs but hopefully they should all come to a similar conclusion regarding heat losses and pump sizing.

    Heatpumps do work but the systems do need to be properly designed and installed. Those who just bung one on in place of a boiler and dont understand how they work or how to use them are those who end up with a system that doesn't perform well and can cost a lot to run especially if you have high flow temperatures and try to run it like a conventional system
    Last edited by matelodave; 02-10-2017 at 9:48 PM.
    Love makes the world go round - beer make it go round even faster
    • Cardew
    • By Cardew 2nd Oct 17, 10:36 PM
    • 27,026 Posts
    • 13,150 Thanks
    Cardew
    • #7
    • 2nd Oct 17, 10:36 PM
    • #7
    • 2nd Oct 17, 10:36 PM
    Just to reinforce the above posts, it is essential that you get the correct installation and to qualify for RHI a registered firm.
    • jeepjunkie
    • By jeepjunkie 19th Oct 17, 10:29 AM
    • 1,384 Posts
    • 1,324 Thanks
    jeepjunkie
    • #8
    • 19th Oct 17, 10:29 AM
    • #8
    • 19th Oct 17, 10:29 AM
    Hi, we are considering replacing our lpg bottle central heating with ASHP. Two questions (looking at Matelodave!);
    I have already replaced all the radiaters (they were all small slimline ones, looked old) with the largest double ones I could fit. Is this ok?
    Secondly, the gubbins that fits inside the house will be in the immersion heater cupboard. Does this make a noise as it will be in our main bedroom?
    Many thanks
    Originally posted by bazm

    The rads have to be sized to the room, with the flow temp and insulation taken into account. The diameter of the pipes to the rads also has to be what the ASHP manufacturer says they must be. Ideally pipes should be insulated to under the floor. Otherwise....
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