I am wondering if someone can point me in the direction of a schematic for a space heating only system.
I have an outbuilding with quite a large office/studio. Has 5 radiators. Currently plumbed with a lpg combi boiler. It uses 47kg cylinders. It’s very expensive to run. I have a shower/sink in there. I am thinking of replacing the heating only with an ASHP and keeping the combi for shower/sink as this is used very infrequently. Then no storage of water that wouldn’t really be used!
I have been trying to find a schematic for an ASHP for space heating only. Looking to buy something low cost, and run through the radiators at modest temperature. I just want to see what else I would need to buy in terms of pumps, valves etc to see what it would cost in total. You can get 7-8kw monobloc units very competitively priced. So it seems feasible.
Any pointing in the right direction would be appreciated!
What’s the expected heat loss of the outbuilding? If small or well insulated then you may get away with a smaller heat pump. Also important to know how big your radiator are.
The alternative route to consider is an air-to-air heat pump, which can also do cooling in the summer. This may work out simpler and cheaper, though means discarding the rads you already have.
I don’t have a calculation. It’s well insulated overall. Anecdotally, I have a 5kw wood burner. It warms up the place pretty well. It heated last night from 12 degrees to 18 in about 2-3hours when it was -2 outside! Floor area is about 70sqm.
I thought about air to air but there are a couple of rooms, so was aiming to use the radiators to heat the whole place uniformly, but cooling in the summer is attractive! Something to think about.
I mean you just connect the heatpump directly to the flow and return, if not needed valve for hot water, and maybe add a volumizer if needed. Couldn’t be simpler. Get a heat pump with inbuilt pump. I assume you already have suitable expansion vessels and pressure release value etc. Pretty plug and play - with a self contained heat pump.
Will you heat it all the time? If not you’ll need something oversized to bring back to temp - and or this might be where air to air is better.
Use heatpunk to try work out heatloss. Or use calculations from gas burnt to kW to understand HP size needed.
The ideal situation for a home is for the heat pump to run continuously, keeping the inside at a consistent temperature. 5 kW may be too big in that case, though there aren’t many [A2W] units that are smaller.
On the other hand, if the outbuilding is only in use for part of the day and heated when needed, then 5 kW might work out. It won’t be the most efficient way to run it, but probably still cheaper than LPG.
This has air-to-air written all over it… Would be much cheaper to install, with quick heating response times and the added bonus of cooling when you need it.
Thanks all. Will check out air to air systems. Sounds like good advice. I don’t have much experience with them versus air to water but looks like a good option!
I’ve recently had a similar building newly-built and went air-to-air for the reasons others have outlined. The shower and sinks are on instantaneous electric heaters so I’ve got no need for stored hot water and air-to-air is a very good fit for the intermittent usage of the building (whereas e.g. underfloor heating would be rubbish).
I ended up with a Daikin ‘multi-split’ system and 3 indoor units: 2 in a long, thin workshop (75 m^2) and 1 in an adjacent utility room (25 m^2). 3 separate systems, each with their own outdoor unit, would have been cheaper (and slightly more efficient?) but I didn’t want 3 outdoor fan units cluttering up the place so paid the extra for the ‘multi-split’ with a single outdoor unit.
The refrigerant gas runs through the pipework between the outdoor unit and the indoor units so you’d need an F-gas certified person to install and maintain an air-to-air system.