A couple of A2A heat pump questions

[DanDee]

 

28 minutes ago, Beelbeebub said:

Making it so you can run a flow and return pair around and locally branch off for each emmiter, like we do with rads, would be a big improvement. 

VRF/VRV is what you are referring to, but the extra bits cost more money

and the more you go away from single split/monoblock the lower the efficiency

 

Changing just the A2W outdoor unit in 10-15-20 years, definetly better/easier.

Edited September 11, 2023 by DanDee

[Beelbeebub]

21 minutes ago, DanDee said:

 

VRF/VRV is what you are referring to, but the extra bits cost more money

and the more you go away from single split/monoblock the lower the efficiency

 

Changing just the A2W outdoor unit in 10-15-20 years, definetly better/easier.

Wouldn't need the full "heat and cool simultaneously" vrf package. 

 

Conceptually I can't see any reason why the head untis can't be connected to a common flow return pair and just have a servo valve to shut them off on the flow side if not needed. The compressor unit doesn't care if there is one condenser coil or several, it just sees pressure temp at outlet and pressure temp and inlet. 

 

Deforst would be trickier without a thermal mass to draw hear from. 

 

That could be solved by using a DHW tank. 

[DanDee]

22 minutes ago, Beelbeebub said:

Wouldn't need the full "heat and cool simultaneously" vrf package. 

 

Conceptually I can't see any reason why the head untis can't be connected to a common flow return pair and just have a servo valve to shut them off on the flow side if not needed. The compressor unit doesn't care if there is one condenser coil or several, it just sees pressure temp at outlet and pressure temp and inlet. 

 

Deforst would be trickier without a thermal mass to draw hear from. 

 

That could be solved by using a DHW tank. 

Not every VRF is "heat and cool simultaneously", you actully would have to have the dedicated 3 pipe unit for that.

There are mini vrf's 12kW using the same indoor units as single splits, with external expansion valves, but you are going towards commercial in a residential place(noise), they are more expensive than mini splits.

 

 

Check Samsung TDM Plus

 

 

Edited September 11, 2023 by DanDee

[DanDee]

24 minutes ago, DanDee said:

Not every VRF is "heat and cool simultaneously", you actully would have to have the dedicated 3 pipe unit for that.

There are mini vrf's 12kW using the same indoor units as single splits, with external expansion valves, but you are going towards commercial in a residential place(noise), they are more expensive than mini splits.

 

 

Check Samsung TDM Plus

 

 

 

I forgot about the commercial non vrf multi unit split.

 

 

 

 

 

 

 

https://www.toshiba-aircon.co.uk/wp-content/uploads/2022/08/Toshiba-Retail-Price-List-2022-UK-effective-14-March.pdf

 

 

Edited September 11, 2023 by DanDee

[Beelbeebub]

Point taken about the expansion valves which you would need for cooling 

 

But these would be primarily for heating. So the single expansion valve in in the outdoor unit would suffice. 

 

Outdoor compressor creates hot, high pressure gas. This flows around to each head unit.

 

Each head unit would iod have 4 ports, flow in, flow out, return in, return out. The "out" ports would be blanked off at the last unit. And a servo on off valve in either allowing the flow gas into the unit or blocking it. 

 

The hot high pressure gas then either condenses to a room temp high pressure liquid and joins the return line. or is blocked and doesn't flow through that coil at all. 

 

The room temp high pressure liquid collects together in the common return pipe and flows to the outside unit. 

 

There is passes through the single expansion valve. 

 

 

[DanDee]

8 minutes ago, Beelbeebub said:

Point taken about the expansion valves which you would need for cooling 

 

But these would be primarily for heating. So the single expansion valve in in the outdoor unit would suffice. 

 

Outdoor compressor creates hot, high pressure gas. This flows around to each head unit.

 

Each head unit would iod have 4 ports, flow in, flow out, return in, return out. The "out" ports would be blanked off at the last unit. And a servo on off valve in either allowing the flow gas into the unit or blocking it. 

 

The hot high pressure gas then either condenses to a room temp high pressure liquid and joins the return line. or is blocked and doesn't flow through that coil at all. 

 

The room temp high pressure liquid collects together in the common return pipe and flows to the outside unit. 

 

There is passes through the single expansion valve. 

 

 

 

Chop the water heat exchanger from a monobloc and connect the pipes

 

[HughF]

11 hours ago, Beelbeebub said:

The decoupling thing is the one bit that attracts me to a2w. 

 

Radiators, pipes etc are commodity items. More or less interchangeable from a wide variety of manufacturers and suppliers.

 

You dint need to fit vaillant radiators because you have a vaillant boiler. Or Baxi radiators if you have a baxi boiler. 

 

Even if you have some weird old boiler that nobody makes any more, you can fit a rad to it. 

 

If a2a units were the same that woukd be a big plus. 

 

Also, a2a units seem to usually use a separate flow return pair to each emitter. Making it so you can run a flow and return pair around and locally branch off for each emmiter, like we do with rads, would be a big improvement. 

 

If they could do that then moving the country to HPs would be a case if fitting a2a systems "in parallel" with the exisiting gas system. That would be there for DHW and for peace of mind about "what if my heatpump can't keep me warm in winter". 

 

After a few seasons where people realise they never use the gas boiler they'll be ready to switch fully 

Vrf/vrv systems are 2 pipe, using what are called ‘refnets’ (branches) to supply liquid and vapour to the indoor units. Just like a flow/return pair.

 

If you want heat recovery then it becomes a 3 pipe system and the reversing valves are inside the air handlers/indoor units. Suck the heat out of your server room and dump it into your hot water tank, whilst cooling the other rooms…. It’s genius.

[Beelbeebub]

46 minutes ago, HughF said:

Vrf/vrv systems are 2 pipe, using what are called ‘refnets’ (branches) to supply liquid and vapour to the indoor units. Just like a flow/return pair.

 

If you want heat recovery then it becomes a 3 pipe system and the reversing valves are inside the air handlers/indoor units. Suck the heat out of your server room and dump it into your hot water tank, whilst cooling the other rooms…. It’s genius.

That would be great, especially for DHW and cooling during the summer. 

 

The main thing for the UK is we need an easy to retrofit system. At the moment we don't have enough installers who are competent in either a2a or a2w systems (either fgas certified or having the detailed knowledge to make a2w systems operate efficiently) to fit enough systems. 

 

A2W has some advantages of we can leverage the large base of heatijg engineers used to gas boilers and wet systems. But does have to be a compete switchover 

 

A2W would require fgas certification or similar. But would potentially allow for parallel installs. Which might ease the user anxiety. Alaonpfovides cooling which may be important. And the overall equipment footprint is lower. 

[JohnMo]

There's an Italian ASHP A2W that can do cooling and hot water heating at the same time. The cylinder has an additional coil for refrigerant, the refrigerant is diverted to cylinder during cooling mode.

[HughF]

2 hours ago, JohnMo said:

There's an Italian ASHP A2W that can do cooling and hot water heating at the same time. The cylinder has an additional coil for refrigerant, the refrigerant is diverted to cylinder during cooling mode.

I believe that most of the splits from daikin with an internal ‘hydraulic/cylinder’ module work this way. F-gas lines into the fridge/freezer sized thing.

[JohnMo]

The one I'm thinking about is a monobloc, with two additional connections for refrigerant.

 

https://www.appliancesdirect.co.uk/bct/heating/monobloc-heat-pumps

 

You need to go into the installer instructions to find the detail, you also need to use their cylinder.

[HughF]

8 minutes ago, JohnMo said:

The one I'm thinking about is a monobloc, with two additional connections for refrigerant.

 

https://www.appliancesdirect.co.uk/bct/heating/monobloc-heat-pumps

 

You need to go into the installer instructions to find the detail, you also need to use their cylinder.

I was looking at the installation instructions for that very unit just last week, but on the Argo website. Looks like a great system, with their external e-mix tank.

[magnayn]

15 hours ago, DanDee said:

Check Samsung TDM Plus

 

This is super interesting 👍

 

One question: how does this affect efficiency? I look at our house, and wonder if when we eventually go heatpump (my view is it's economically unviable for us right now), our large UFH downstairs would fit well, but the rest of the house much less -- a split between _some_ a2w (mostly downstairs) and _some_ a2a (mostly upstairs) would be the best solution. Having multiple outdoor units - although we have a location that we could likely put them wihout looking _too_ terrible - would be nice to avoid.

Is there anywhere good as an information resource about this kind of thing? Vendors are really, really bad about advertising their own products, let alone what actual stuff is possible..

[DanDee]

21 minutes ago, magnayn said:

Is there anywhere good as an information resource about this kind of thing? Vendors are really, really bad about advertising their own products, let alone what actual stuff is possible..

https://www.climamarket.bg/wp-content/uploads/TDB-EHS-TDM-Plus-for-Europe-R410A-50Hz-HP-Ver1.0_170313.pdf

 

 

 

22 minutes ago, magnayn said:

One question: how does this affect efficiency? 

16 hours ago, DanDee said:

and the more you go away from single split/monoblock the lower the efficiency