Sorry....another slate thread!

[Stable3]

9 hours ago, Conor said:

Ours are del Carmen prime.

I’ve got del carmen samples ordered thanks 

[SteamyTea]

42 minutes ago, Stable3 said:

not being able to have a quick boost of heat if needed

A heat pump is not used like a gas/oil boiler.

 

You set the temperature you like your house to be at (this can take a few days and a bit of work as the installers usually leave them on default settings) and the heat pump warm and cool as necessary.

45 minutes ago, Stable3 said:

very well insulated! Plus it’s the size of your average Wendy house

You won't be needing a wood burner then.

[Iceverge]

2 minutes ago, SteamyTea said:

A heat pump is not used like a gas/oil boiler.

 

 

 

I would argue this only a consequence of the power output you can buy them in. 

 

If someone made a 40kW ASHP as accessable as a 40kW gas boiler people would probably use them in the same way. (Lots of technical and cost roadblocks with that approach I know).

 

Most houses don't need heating 24/7 as people go to school, work, the pub etc and even a very low energy demand house will use less energy if it'a one heated intermittently. 

 

To allow for this you need high power heat generators and emitters to get up to temperature quickly and this is where a 5kW ASHP with widely spaced UFH pipes just doesn't cut the mustard. 

 

However get the biggest A2A unit you can fit with a appropriate fan coils and I don't see why it wouldn't work. 

 

 

 

 

 

 

 

 

 

 

[SteamyTea]

12 minutes ago, Iceverge said:

would argue this only a consequence of the power output you can buy them in. 

Yes, no, kind of.

 

Combustion boilers are usually sized to heat the DHW so they can run a bath or a couple of showers.

The space heating power requirements are generally a lot lower.

Gas boilers have good modulation i.e. 25 kW down to 3 kW.

A correctly sized ASHP of say 6 kW may only modulate down to just below 4 kW.

There can be a bit of trickery with the flow temperatures, but to keep the CoP high, they are quite limited in power delivery.

This is why they need to be sized correctly. Just fitting an oversized unit would not work, it would sense the return temperature, see it is close to the flow temperature, then throw an error and shut down.

Edited November 13 by SteamyTea

[Iceverge]

9 minutes ago, SteamyTea said:

would sense the return temperature, see it is close to the flow temperature, then throw an error and shut down.

 

Unless you had appropriately powerful heat emitters that could ensure a low enough return temperature. 

 

Like very closely spaced UFH in a highly conductive screed or multiple fan coils or giant radiators. 

 

[SteamyTea]

2 minutes ago, Iceverge said:

 

Unless you had appropriately powerful heat emitters that could ensure a low enough return temperature

Yes.

Kills the CoP though.

 

We tend to let houses rapidly heat up from a cold temperature as that is what we have got used to over the last 60 years.

We then let them cool down too much, as we know we can easily blast them with 30 kW of power at a delivery temperature around 70°C.

Not many people (even in here) ever question, or measure, how efficient their boilers are.

Shame that has boilers don't have energy meters on them.

Would scare a lot of people when they see efficient numbers in the 50 to 60% range.

A lot of people quite gas boilers as being 95% in efficiency. Not many will be once installed.

It is a bit like car MPG. I can get better than the official figures, sometimes. But most of the time I am below them. Not surprising as my first journey in the morning has 9 sets of traffic lights, 3 roundabouts, two steep hills, and 5 junctions. All in a 30 MPH zone.

And that is over 2 miles.

So cold engine, stop start and generally 3^rd gear.

Bloody amazing that at the end of the week my Mondeo averages out 65 MPG.

[G and J]

I am sitting in front of a woodburner, nice and toasty.  The rest of the house is circa 15/16C, because it was mild outside today.
 

I grew up in a house that in winter had frost on the inside of the windows.  As kids we used the heat of our fingers to draw faces, etc. in the frost.

 

Life was f cold for half the year apart from short burst of lovely and warm.  
 

So it’s no wonder that millions of brits struggle with the notion of continuous comfortable temperatures.  I can’t imagine living in a house (i.e. the one I’m planning to build) where it’s not cold first thing.  It’s alien to me. 
 

Perhaps I should cut myself (and others) some slack in not understanding how such new fangled systems will work.   Perhaps I should buy a few more pairs of shorts too.

[Iceverge]

28 minutes ago, SteamyTea said:

Yes.

Kills the CoP though.

Only if you raise the flow temp. 

 

You wouldn't need to do this if you just tripled or quadrupled the amount of radiators. 

 

Roughly 50m² of rads at a flow temp of 70 degrees would deliver the same amount of energy per second (power) as about 170m² of radiators at a flow temp of 35deg. 

 

This is what I mean by increasing the power of the emitters.

 

And higher power emitters will always allow for a lower flow temperature.

 

 

 

 

 

 

 

[SteamyTea]

8 minutes ago, Iceverge said:

Roughly 50m² of rads at a flow temp of 70 degrees would deliver the same amount of energy per second (power) as about 170m² of radiators at a flow temp of 35deg.

50m² is about the same as my total floor area, 170m², would include the walls and the roof.

 

I know what you are say, and using forced air heating with a heat pump is away around it.

But then why would you for no runnign cost savings.

Edited November 13 by SteamyTea

[Stable3]

3 hours ago, SteamyTea said:

 

You won't be needing a wood burner then.

Needing and wanting are two different things ST! I’ve always dreamed of a log burner…. I’ll leave the door open if I have to 😆

 

on a serious note - and I can’t speak as eloquently or knowledgeably on the subject as some others here, I find I spend a lot less on the heating (with our current gas boiler) when I keep the thermostat at a constant temperature (say 16) and just a boost up to 18 if it’s cold.

 

When I turn it off and on and the temperature drops down (which it does quickly in our current poorly insulated house) it costs way more to get back up to temperature.  I do agree I don’t like to have heating on in the bedroom and like the room to be cold when I wake up!  Not too sure how that’s going to work with ufh as we’ve been advised not to have too many zones?

[scottishjohn]

1 hour ago, Stable3 said:

Needing and wanting are two different things ST! I’ve always dreamed of a log burner…. I’ll leave the door open if I have to 😆

 

on a serious note - and I can’t speak as eloquently or knowledgeably on the subject as some others here, I find I spend a lot less on the heating (with our current gas boiler) when I keep the thermostat at a constant temperature (say 16) and just a boost up to 18 if it’s cold.

 

When I turn it off and on and the temperature drops down (which it does quickly in our current poorly insulated house) it costs way more to get back up to temperature.  I do agree I don’t like to have heating on in the bedroom and like the room to be cold when I wake up!  Not too sure how that’s going to work with ufh as we’ve been advised not to have too many zones?

I remember reading somewhere that for every 1 degree you over heat your house  it can be 7% more cost 

 but you stated the obvious --up the insulation as first job choice  then type  of heating system next 

[SteamyTea]

6 hours ago, Stable3 said:

Not too sure how that’s going to work with ufh as we’ve been advised not to have too many zones

By spacing the UFH pipework to suit the losses for each room.

Why a room by room heat loss calculations are done.

[JohnMo]

6 hours ago, Stable3 said:

agree I don’t like to have heating on in the bedroom and like the room to be cold when I wake up!  Not too sure how that’s going to work with ufh as we’ve been advised not to have too many zones?

We have UFH through out, all acting as a single zone.

 

I flip about how I run the system, weather compensation and batch charging, but have over the last week been running a slightly elevated flow temp over night (around 32), then using floor as a storage heater (batch charge). But have less UFH pipes in the bedroom so a lower output (or you could reduce flow through those loops). We keep the bedroom doors closed throughout the day, so they don't get as warm, as the rest of the house. So most of yesterday the house had been at just above 21, bedrooms just below 20.

 

By 10pm the house has cooled to just below 21, heating generally off until after midnight. It then starts up again and charges the floor. Heating the floor is a slow affair, so by 0730 the house is back to 21.

 

Just use a simple 0.1 hysterisis thermostat to control. 

 

Thing with UFH it's very different to radiators, the change in room temp or house temp takes an age to change. But all done with flow temps are quite lot lower than radiators.

[Stable3]

2 hours ago, JohnMo said:

We have UFH through out, all acting as a single zone.

 

I flip about how I run the system, weather compensation and batch charging, but have over the last week been running a slightly elevated flow temp over night (around 32), then using floor as a storage heater (batch charge). But have less UFH pipes in the bedroom so a lower output (or you could reduce flow through those loops). We keep the bedroom doors closed throughout the day, so they don't get as warm, as the rest of the house. So most of yesterday the house had been at just above 21, bedrooms just below 20.

 

By 10pm the house has cooled to just below 21, heating generally off until after midnight. It then starts up again and charges the floor. Heating the floor is a slow affair, so by 0730 the house is back to 21.

 

Just use a simple 0.1 hysterisis thermostat to control. 

 

Thing with UFH it's very different to radiators, the change in room temp or house temp takes an age to change. But all done with flow temps are quite lot lower than radiators.

Thank you - that’s really helpful