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Is this 6kW of electrical consumption, or 6kW of heat output?

How does one know if you need pipes and radiators changed to accommodate the different flow rates and temperatures of a heat pump vs a gas combi boiler?

dan_b wrote: ↑Fri Sep 22, 2023 11:36 am Is this 6kW of electrical consumption, or 6kW of heat output?

How does one know if you need pipes and radiators changed to accommodate the different flow rates and temperatures of a heat pump vs a gas combi boiler?

6kW is heat output.

If you have an old system with big rads plumbed in 15/22mm then youre fine. New-build since the 90s with teeny rads plumbed in microbore and you'll need to rip out everything!

I have looked in to this as the cottage is piped with microbore, from what I have researched its not black and white, check out these links for more background.





My issue with all of this is people seem to talk about ASHP for heating OR for DHW seldom for both, but they also say that if you have a heat pump you need a cylinder, so if you have a cylinder isn't this effectively a low loss header as per option 3 in the first link above and in which case the micro bore doesn't really mater as there's a second circulation pump for the rads and the flow rate for the ASHP is unlimited as its the 22mm bore coil in the tank isnt it ?

Moxi

dan_b wrote: ↑Fri Sep 22, 2023 11:36 am Is this 6kW of electrical consumption, or 6kW of heat output?

How does one know if you need pipes and radiators changed to accommodate the different flow rates and temperatures of a heat pump vs a gas combi boiler?

Dan, I signed up on Octopus site to be contacted when they get this far North. I expect that to be a couple of years and hopefully they'll be doing larger units by then?

It's good to see a company actively getting into and on with it.

Moxi wrote: ↑Fri Sep 22, 2023 12:20 pm
My issue with all of this is people seem to talk about ASHP for heating OR for DHW seldom for both, but they also say that if you have a heat pump you need a cylinder, so if you have a cylinder isn't this effectively a low loss header as per option 3 in the first link above and in which case the micro bore doesn't really mater as there's a second circulation pump for the rads and the flow rate for the ASHP is unlimited as its the 22mm bore coil in the tank isnt it ?

Moxi

Nowty Towers can be run in this arrangement with both DHW tank and heating in parallel. But the problem is the lower temp in the rads will bring down the temp in the hot water tank to a tepid temp and not workable for DHW.

Hmm. My rads in my flat are quite big - they're all dual rads in fact - but they seem to have plastic pipes which are thinner than the metal fittings - is that microbore?
And I have a combi boiler here now, no hot water tank, so is that not suitable either?

Stinsy wrote: ↑Fri Sep 22, 2023 11:44 am

dan_b wrote: ↑Fri Sep 22, 2023 11:36 am Is this 6kW of electrical consumption, or 6kW of heat output?

How does one know if you need pipes and radiators changed to accommodate the different flow rates and temperatures of a heat pump vs a gas combi boiler?

6kW is heat output.

If you have an old system with big rads plumbed in 15/22mm then youre fine. New-build since the 90s with teeny rads plumbed in microbore and you'll need to rip out everything!

nowty wrote: ↑Fri Sep 22, 2023 12:40 pm

Moxi wrote: ↑Fri Sep 22, 2023 12:20 pm
My issue with all of this is people seem to talk about ASHP for heating OR for DHW seldom for both, but they also say that if you have a heat pump you need a cylinder, so if you have a cylinder isn't this effectively a low loss header as per option 3 in the first link above and in which case the micro bore doesn't really mater as there's a second circulation pump for the rads and the flow rate for the ASHP is unlimited as its the 22mm bore coil in the tank isnt it ?

Moxi

Nowty Towers can be run in this arrangement with both DHW tank and heating in parallel. But the problem is the lower temp in the rads will bring down the temp in the hot water tank to a tepid temp and not workable for DHW.

So why is the government and the plumbing and heating industry saying "have a heat pump"? if a heat pump can only do one thing or the other ? Theres something missing in my knowledge here and its bugging me - but surely we are not being asked by HM government to buy two heat pumps one for DHW and another for CH. What is the KW rating for your DIY system Nowty ?

Moxi

Moxi wrote: ↑Fri Sep 22, 2023 12:57 pm

nowty wrote: ↑Fri Sep 22, 2023 12:40 pm

Moxi wrote: ↑Fri Sep 22, 2023 12:20 pm
My issue with all of this is people seem to talk about ASHP for heating OR for DHW seldom for both, but they also say that if you have a heat pump you need a cylinder, so if you have a cylinder isn't this effectively a low loss header as per option 3 in the first link above and in which case the micro bore doesn't really mater as there's a second circulation pump for the rads and the flow rate for the ASHP is unlimited as its the 22mm bore coil in the tank isnt it ?

Moxi

Nowty Towers can be run in this arrangement with both DHW tank and heating in parallel. But the problem is the lower temp in the rads will bring down the temp in the hot water tank to a tepid temp and not workable for DHW.

So why is the government and the plumbing and heating industry saying "have a heat pump"? if a heat pump can only do one thing or the other ? Theres something missing in my knowledge here and its bugging me - but surely we are not being asked by HM government to buy two heat pumps one for DHW and another for CH. What is the KW rating for your DIY system Nowty ?

Moxi

A lot of combi-boilers can't do both at the same time anyway either... Surely the answer is to use zone valves to hot up the DHW as much as you want first, then close it off and run the CH instead?
It's how my gas system works. (When I went to work it got the water hot enough to shave before switching over to heating the house. It didn't cool the DHW because the coil in the tank can heat water above it, but not cool that water!)

dan_b wrote: ↑Fri Sep 22, 2023 12:43 pm Hmm. My rads in my flat are quite big - they're all dual rads in fact - but they seem to have plastic pipes which are thinner than the metal fittings - is that microbore?
And I have a combi boiler here now, no hot water tank, so is that not suitable either?

Stinsy wrote: ↑Fri Sep 22, 2023 11:44 am

dan_b wrote: ↑Fri Sep 22, 2023 11:36 am Is this 6kW of electrical consumption, or 6kW of heat output?

How does one know if you need pipes and radiators changed to accommodate the different flow rates and temperatures of a heat pump vs a gas combi boiler?

6kW is heat output.

If you have an old system with big rads plumbed in 15/22mm then youre fine. New-build since the 90s with teeny rads plumbed in microbore and you'll need to rip out everything!

Yes the plastic pipe with inserts is "micro bore" according to multiple sources I have studied and yes you need a HWC to store the energy - another major issue for me and others with no space for a HWC. My current plan is to proceed like Nowty towers and have the whole lot fitted in to a lean-to and pipe through the wall to the internal plumbing, then insulate the snizwhiz out of the lean to and transfer pipework to preserve efficiency. But that only works if the one heat pump can effectively run the DHW and the CH which at present is very hard to determine on most sites for heat pumps ?????

Moxi