Bad advice from the BBC

[Yuff]

Yuff,

Just realised you mentioed changing the HP output temperature but most UFH manifolds (at least those I've seen) have a thermostatic mixer valve to regulate the temperature in the UFH. Assuming yours does, did you change that setting aswell or just the HP?
[/quote]

I’ve only just changed the heat pump,at the moment. The manifold I’ve left at 50 but I assume only 45 will go into the UFH.
Not an expert but just trial and error. I might try stinsy’s suggestion and go as low as 35 for longer.
When I got the Ashp’s fitted the advice I read back then was a lower flow for longer was the most efficient way

[ecogeorge]

[/quote]
I’ve only just changed the heat pump,at the moment. The manifold I’ve left at 50 but I assume only 45 will go into the UFH.
Not an expert but just trial and error. I might try stinsy’s suggestion and go as low as 35 for longer.
When I got the Ashp’s fitted the advice I read back then was a lower flow for longer was the most efficient way
[/quote]
That seems very hot ?? is the floor mot unbearable ???
In a previous house with ground source i ran at 34c
George

[Marcus]

Yeah! The consumer program on radio4 repeats the mantra that “rooms should be heated to 21℃ For health reasons” which I’ve never been able to understand. For all of human history buildings were much colder than that in winter. It is only since the 80s that bedrooms have been that hot. Anyway we’re a 16℃ Family, with jumpers!

And you’re correct, lower is better for flow temp on radiators. You are supposed to heat your DHW tank to 60℃ Once a fortnight. However in reality this is only needed if your DHW isn’t used for weeks on end.

I have to say that the quality of journalism on the Beeb has slumped considerably in recent years. Anything technical (including renewable energy, energy efficiency, BEVs, etc.) is reported with glaring errors and omissions.

I have turned our heat pump up to 50°c but I am thinking maybe I should turn it down to 45°c and have it on for longer ……..
No one seems to know the answer, constant lower temp or higher less often
At 45°c the UF heating and rads seem to work just as well. I use the immersion off peak for the DHW

Running the heat pump at a lower flow temp should give you a higher COP and lower running costs. With ufh you should be able to go lower than 45 (but with the caveat that i don't know your floor + rad size relative to house size, or heat losses.

I'm still experimenting with mine ( 10kw grant aerona) but over the past week or so I've had the timer set to turn on at noonish and off around 3pm. The climatic curve is set to 35c at an outside temp of -8c, and 23c (lowest allowed) at 20c - not that I'd have the heating on at that temp. It's currently outputting at aroind 28c and typically uses about 1.5 - 3 kwh over 3hrs.

The 35c at outside temp of -8 might be way off - i won't know til it gets colder, but at current ambient temps(low - mid teens in the day, mid to high single digits overnight ) 28c flow for 3 hrs works out about right: the house temp peaks around 18 or 19c at 5pm ish, and dips to about 17.5, despite having a window open all the time for the cat

Lower flow temp for a longer time is better for performance, but I'm not yet sure how low i could go before it starts cycling, or the standing losses of circulation pumps etc adversely affect cop.

I'm not sold on leaving on 24hrs, but then i have solar power to use in the middle of the day, and noon - midafternoon usually has the highest ambient temp to boost cop. Will have to wait and see what winter brings...

[Yuff]

I’ve only just changed the heat pump,at the moment. The manifold I’ve left at 50 but I assume only 45 will go into the UFH.
Not an expert but just trial and error. I might try stinsy’s suggestion and go as low as 35 for longer.
When I got the Ashp’s fitted the advice I read back then was a lower flow for longer was the most efficient way
[/quote]
That seems very hot ?? is the floor mot unbearable ???
In a previous house with ground source i ran at 34c
George
[/quote]

My wife likes it 23/24°c so I am fighting a losing battle before I start
Upstairs if it’s 22 it’s too hot to go to sleep, ideally 20 ish which is what I am aiming for.

[Yuff]

Yeah! The consumer program on radio4 repeats the mantra that “rooms should be heated to 21℃ For health reasons” which I’ve never been able to understand. For all of human history buildings were much colder than that in winter. It is only since the 80s that bedrooms have been that hot. Anyway we’re a 16℃ Family, with jumpers!

And you’re correct, lower is better for flow temp on radiators. You are supposed to heat your DHW tank to 60℃ Once a fortnight. However in reality this is only needed if your DHW isn’t used for weeks on end.

I have to say that the quality of journalism on the Beeb has slumped considerably in recent years. Anything technical (including renewable energy, energy efficiency, BEVs, etc.) is reported with glaring errors and omissions.

I have turned our heat pump up to 50°c but I am thinking maybe I should turn it down to 45°c and have it on for longer ……..
No one seems to know the answer, constant lower temp or higher less often
At 45°c the UF heating and rads seem to work just as well. I use the immersion off peak for the DHW

Running the heat pump at a lower flow temp should give you a higher COP and lower running costs. With ufh you should be able to go lower than 45 (but with the caveat that i don't know your floor + rad size relative to house size, or heat losses.

I'm still experimenting with mine ( 10kw grant aerona) but over the past week or so I've had the timer set to turn on at noonish and off around 3pm. The climatic curve is set to 35c at an outside temp of -8c, and 23c (lowest allowed) at 20c - not that I'd have the heating on at that temp. It's currently outputting at aroind 28c and typically uses about 1.5 - 3 kwh over 3hrs.

The 35c at outside temp of -8 might be way off - i won't know til it gets colder, but at current ambient temps(low - mid teens in the day, mid to high single digits overnight ) 28c flow for 3 hrs works out about right: the house temp peaks around 18 or 19c at 5pm ish, and dips to about 17.5, despite having a window open all the time for the cat

Lower flow temp for a longer time is better for performance, but I'm not yet sure how low i could go before it starts cycling, or the standing losses of circulation pumps etc adversely affect cop.

I'm not sold on leaving on 24hrs, but then i have solar power to use in the middle of the day, and noon - midafternoon usually has the highest ambient temp to boost cop. Will have to wait and see what winter brings...

Thanks Marcus, that sounds a bit too technical for my layman skills in heating etc
I’m slowly dropping the heat pump temp and seeing how it affects the efficiency and temp. Wearther here is quite stable this week so should get my some decent figures….

[AGT]

I’ve only just changed the heat pump,at the moment. The manifold I’ve left at 50 but I assume only 45 will go into the UFH.
Not an expert but just trial and error. I might try stinsy’s suggestion and go as low as 35 for longer.
When I got the Ashp’s fitted the advice I read back then was a lower flow for longer was the most efficient way

That seems very hot ?? is the floor mot unbearable ???
In a previous house with ground source i ran at 34c
George
[/quote]

My wife likes it 23/24°c so I am fighting a losing battle before I start
Upstairs if it’s 22 it’s too hot to go to sleep, ideally 20 ish which is what I am aiming for.
[/quote]


I think certain room stats allow you to set the calibration on the thermostat, for example mine allows the temp to be set higher-1 deg higher than it actually is to let SWMBO see it and convince herself it’s just her…

[Yuff]

I’ve only just changed the heat pump,at the moment. The manifold I’ve left at 50 but I assume only 45 will go into the UFH.
Not an expert but just trial and error. I might try stinsy’s suggestion and go as low as 35 for longer.
When I got the Ashp’s fitted the advice I read back then was a lower flow for longer was the most efficient way

That seems very hot ?? is the floor mot unbearable ???
In a previous house with ground source i ran at 34c
George

My wife likes it 23/24°c so I am fighting a losing battle before I start
Upstairs if it’s 22 it’s too hot to go to sleep, ideally 20 ish which is what I am aiming for.
[/quote]


I think certain room stats allow you to set the calibration on the thermostat, for example mine allows the temp to be set higher-1 deg higher than it actually is to let SWMBO see it and convince herself it’s just her…
[/quote]

It’s been 24°c in the room, last winter and she complained it was too chilly.
She did take a hot water bottle to Dubai 2 weeks ago

[resybaby]

The traditional water cylinder/hot tank is supposed, according to the old BS6700 now replaced with some other guidance document whose reference number currently escapes me, to be heated to 60'c, the distributing pipework distributing water at 55'c, and the outlet temps supposed to be 50'c.
Combi's have a struggle to output at 60'c with any decent flowrate.
Legionella is active between 20-50'c, hence these temps being the norm.
Then there of course is all the thermostatic temperature control devices on the likes of baths/basins etc, which reduce those outlet temps further depending on the building usage/occupancy.

I had to inspect and enforce this stuff on behalf of the Secretary of State as part of my Regulation Enforecement role. Proper uphill battle and practical minefield. Oddly nobody gave a flying **** until, of course, someone got seriously ill or died.