Prepping for ASHP and sizing - Heat loss calcs confusion

[jack]

15 hours ago, SimonD said:

So in @jack's case, I can presume that the UFH works well to keep the upstairs warm in winter, but from the charts, shows it has no effect on upstairs for cooling and as he says 'unsurprisingly.' This demonstrates it isn't a whole house cooling strategy, even if it does provide comfort downstairs. Forgive me if I'm wrong @jack?

 

No, that's accurate.

 

Bedrooms are cool but acceptable (to me if not my wife!) in winter. This is the upstairs hall temperature in January and February (lowest is 17.4 °C, highest is 20.3 °C):

 

 

I'll be tweaking the control loop for next winter to see what sort of impact I can have on the lowest temps, as I now have more info available to let me analyse what's going on.

 

If I were doing this all again, I'd consider tiling upstairs with a wet UFH system. Rugs down in winter for underfoot warmth, along with intermittent mild heating to keep the temp relatively stable. Rugs up in summer, with cooling as needed.

[jack]

17 hours ago, JohnMo said:

... better than the cold draft and head ache it caused.

I get all sorts of headaches with dry air - same in winter when we have cold, dry periods. It's all sinus related.

[mistake_not]

Really useful thanks @jack.

 

I took a quick look at the Panasonic unit and on the face of it the specs look good and folks seem to have been able to integrate fully to HA using ESP32.

 

22 hours ago, jack said:

 

 

 

Annoyingly the image seems to have a problem and won't load 😞

[jack]

15 minutes ago, mistake_not said:

Annoyingly the image seems to have a problem and won't load 😞

 

That's odd. It's visible to me in both my post and where you quoted it in your reply. 

[marshian]

2 hours ago, jack said:

 

That's odd. It's visible to me in both my post and where you quoted it in your reply. 

 

Probably in your cache - I can't see it either

[jack]

3 hours ago, marshian said:

 

Probably in your cache - I can't see it either

 

Not visible on my phone, so I think you're right.

 

I'll post it again tomorrow when I'm back at my desk.

[jack]

@mistake_not @marshian

 

This is the image (I also added it back to the first post):

 

[SteamyTea]

I missed the first page of this discussion.

I like the bits about 'radiative' energy.

 

https://physics.stackexchange.com/questions/679165/stefan-boltzmann-law-applied-to-the-human-body

[SimonD]

40 minutes ago, SteamyTea said:

I missed the first page of this discussion.

I like the bits about 'radiative' energy.

 

https://physics.stackexchange.com/questions/679165/stefan-boltzmann-law-applied-to-the-human-body

 

It's funny, I got sucked in and read all of that. For me, when I was working in tech and in professional services I was primarily a system designer, whether that was an IT system or a system for effective knowledge transfer and exchange, so I particularly liked the last part where it's very correctly pointed out that the physics can isolate systems that are interacting in a complex way, in order to simplify the calculation, but of course in heating a home we're looking at multiple dynamic systems that are always interacting and creating a wider system.

 

This is one of the reasons I get frustrated with heating system design as it's almost ingrained in the industry to design for and then quote a system according to its 'flow temp' or a set 'minimum room temp' - a customer recently asked me what flow temperature I had designed for the system and why I had applied a constant temperature throughout the house. I explained that the flow temp should correctly be constantly fluctuating according to demand and that the changes I'd proposed also have redundancy and resilience built in to accommodate future changes and developments in requirements. 

I recently raised this question with a highly experienced engineer and designer, when I was presented with an example calculation to show how hydraulic separation doesn't necessarily create system inefficiencies. When I asked about control mechanisms and how a dynamic system responds and behaves following constant modulation, the response was silence.

We still have a long way to go to properly understand these interacting systems because most complex of all is how the human body responds and finds comfort within the system.

[mistake_not]

4 hours ago, jack said:

@mistake_not @marshian

 

This is the image (I also added it back to the first post):

 

Ah that's really interesting to see- thank you.

 

Makes me think I should look at something similar for pumps. Given the price of the quotes I have received a self installation (+sparky) might be on the cards...

[JohnMo]

1 hour ago, mistake_not said:

Ah that's really interesting to see- thank you.

 

Makes me think I should look at something similar for pumps. Given the price of the quotes I have received a self installation (+sparky) might be on the cards...

I would try to find the engineering tables for various heat pumps, the minimum modulation figure is more important than the max output figure as your heating requirements are around half your design day for the average heating season day. Plus you will get an idea of expected CoP at you flow temps.