camelot-forum.co.uk

This looks good - speaking as a non-expert in heat pumps
https://www.theengineer.co.uk/content/n ... -heat-pump

Anyone know if the COP of a high temp HP is lower than that of a normal HP, when only heating the radiator water to ~35C/40C?

I'm just wondering, as we have all microbore, so hard to get an ASHP approved. But as we only consume about 6,000kWh of gas pa, and have two A2A units as back up, I'm thinking a high temp unit, would tick any necessary boxes for approval, grant etc. but still provide the heat we need for 95%-99% of the time, at a 'normal' HP temp.

Mart wrote: ↑Fri Sep 15, 2023 2:04 pm Anyone know if the COP of a high temp HP is lower than that of a normal HP, when only heating the radiator water to ~35C/40C?

I'm just wondering, as we have all microbore, so hard to get an ASHP approved. But as we only consume about 6,000kWh of gas pa, and have two A2A units as back up, I'm thinking a high temp unit, would tick any necessary boxes for approval, grant etc. but still provide the heat we need for 95%-99% of the time, at a 'normal' HP temp.

https://www.theecoexperts.co.uk/heat-pu ... heat-pumps

"Is it worth getting a high temperature heat pump?

It's not worth getting a high temperature heat pump, in most cases.

They typically cost 25% more to buy and install than regular heat pumps, they're around 20% more expensive to run, and they won't cut your carbon footprint by as much.

You should usually only buy a high temperature heat pump for a property that's large, extremely hard to insulate, and requires a high amount of hot water.

If your building is listed, or if it's too old for energy efficiency improvements to be a realistic prospect (either financially or practically), a high temperature heat pump may be your best bet.

Otherwise, we'd almost always recommend insulating your home and buying a regular heat pump."

Mart wrote: ↑Fri Sep 15, 2023 2:04 pm Anyone know if the COP of a high temp HP is lower than that of a normal HP, when only heating the radiator water to ~35C/40C?

Mart, I've been looking at Vaillant heat pumps as a possible replacement for my oil boiler and it says that they can output water up to 75C.
But for EN14511 testing it only gives figures up to 65C, the COP's (all at 7C outdoor air temperature) are as follows:
Water 35C - 5.30
Water 45C - 4.10
Water 55C - 3.10
Water 65C - 2.30

The COP of 5.30 is one of the highest I have seen for any domestic ASHP.

Thanks guys, just pondering options. Last winter I ran the combi at it's lowest radiator temp to see how that faired, just as a guide. It was OK for all but 2 weeks. However, it wasn't on 24/7, so maybe not the fairest comparison.

BTW that 6,000kWh figure for gas includes oven and DHW, which seems to be around 100kWh/month in non-heating months.

Fintray wrote: ↑Fri Sep 15, 2023 3:06 pm Mart, I've been looking at Vaillant heat pumps as a possible replacement for my oil boiler and it says that they can output water up to 75C.

When they say "can output water up to 75C", what they mean is the internal gas temp can get up to 75 degrees before the unit trips out. So if you have a ludicrous high flow rate the output water may theoretically get to that temp, but in practise there will be a temp difference between the gas temp and the output water temp, circa 2 to 5 degrees.

Octopus acquired RED and their secret sauce was a technology to inject gas into the exchanger to cool it down when in high temp mode. They also have a secondary exchanger for low temp operations.

Samsung's propane unit also does this.

They will fight the MCS on the ideal pump velocity for this system, I think octopus will try to bump it to 1.5.

As I have said many times before your local one man "
Gas engineer" is now a dodo and large capital intensive businesses can afford to stomp them out and tie customer install performance to the money/grant.