air to water heat pump, direct to radiators, vented?

frankwest12345 · 07-20-13, 07:43 AM

I have just acquired a cheap, used air source heat pump, Activair Trianco 5kW which is supposed to be used for heating hot water in a cylinder but I already have a separate thermal panel system for hot water and want to run five large radiators directly off the heat pump instead. Preferably using a vented system as I have an old gas CH water tank already in position and connected to the radiator circuit (have removed an ancient gas boiler, pump and valves and connections to the hot water cylinder). I have decreased window area by 2/3 and puts lots of insulation in the property so the max 60 degree C output temperature should be reasonably matched to the very large radiators (albeit rather old themselves and flushed a lot of stuff out of them)... I assume the (vented) circuit is identical to that of the boiler and it is just a matter of connecting up to the HP. Any things I should be looking out for?

jeff5may · 07-22-13, 12:12 AM

So from your post, it sounds as if you have an open central heating system with a high point feed & expansion tank. This was connected to a gas boiler which ran through a pump to supply water to radiators to heat the house. You want to put this "mini-split" type heat pump in the boiler's place to heat your home. Correct?

If you removed the boiler's pump and flow controls, you will need to rig up similar items to the heat pump. Otherwise, you will have no way to bypass or prime the heat pump (or radiators) with mains water. You may be able to reuse some of these components if you haven't already thrown them out.

The unit should function to heat the home, but the details are sketchy. A 5kw unit is around 20000 btu, so it is not an especially large capacity unit. It may run a lot more than the gas boiler did to provide the same amount of heat. When it gets cold out, it might not keep up with your heating demands. Then again, it may work just fine. It all depends on what you had before, and the size and heat load of your home.

Without more details, noone can tell you definitively how your proposed system will operate. Please post more details about your system. Pictures are worth thousands of words.

frankwest12345 · 08-02-13, 07:26 AM

the heat pump has a built in pump and comes with a controller so in theory it is just a case of connecting on to the boiler flo and return pipes (having disconnected the boiler) and filling via the feed tank (keeping the vent pipe as I am not keen on building a bomb)

07-20-13, 07:43 AM	#1
frankwest12345 Lurking Renovator Join Date: Aug 2011 Location: Swindon UK Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts	air to water heat pump, direct to radiators, vented? I have just acquired a cheap, used air source heat pump, Activair Trianco 5kW which is supposed to be used for heating hot water in a cylinder but I already have a separate thermal panel system for hot water and want to run five large radiators directly off the heat pump instead. Preferably using a vented system as I have an old gas CH water tank already in position and connected to the radiator circuit (have removed an ancient gas boiler, pump and valves and connections to the hot water cylinder). I have decreased window area by 2/3 and puts lots of insulation in the property so the max 60 degree C output temperature should be reasonably matched to the very large radiators (albeit rather old themselves and flushed a lot of stuff out of them)... I assume the (vented) circuit is identical to that of the boiler and it is just a matter of connecting up to the HP. Any things I should be looking out for?

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07-22-13, 12:12 AM	#2
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	So from your post, it sounds as if you have an open central heating system with a high point feed & expansion tank. This was connected to a gas boiler which ran through a pump to supply water to radiators to heat the house. You want to put this "mini-split" type heat pump in the boiler's place to heat your home. Correct? If you removed the boiler's pump and flow controls, you will need to rig up similar items to the heat pump. Otherwise, you will have no way to bypass or prime the heat pump (or radiators) with mains water. You may be able to reuse some of these components if you haven't already thrown them out. The unit should function to heat the home, but the details are sketchy. A 5kw unit is around 20000 btu, so it is not an especially large capacity unit. It may run a lot more than the gas boiler did to provide the same amount of heat. When it gets cold out, it might not keep up with your heating demands. Then again, it may work just fine. It all depends on what you had before, and the size and heat load of your home. Without more details, noone can tell you definitively how your proposed system will operate. Please post more details about your system. Pictures are worth thousands of words.

08-02-13, 07:26 AM	#3
frankwest12345 Lurking Renovator Join Date: Aug 2011 Location: Swindon UK Posts: 13 Thanks: 0 Thanked 0 Times in 0 Posts	the heat pump has a built in pump and comes with a controller so in theory it is just a case of connecting on to the boiler flo and return pipes (having disconnected the boiler) and filling via the feed tank (keeping the vent pipe as I am not keen on building a bomb)