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Heat loss from thermal stores (and UVCs)


dnb

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The 2 issues are a thermal store needs to store water at a hotter temperature, so that alone means higher losses.

 

Then just about every thermal store I have seen is a copper tank with spray foam insulation, which you can get in different thicknesses but they tend to have a weak link around the connections.

 

Compare that to a Telford Stainless steel unvented cylinder which has the inner stainless steel tank, and an outer solid jacket with the gap full of insulation.  This seems to give a better insulated cylinder with no weak point around the connections.  Lag all the pipework in and out well and I get very little detectable heat loss and the room with the tank is not noticable warmer than other rooms.

 

I wonder why nobody seems to make a thermal store of similar construction and lagging?

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8 hours ago, dnb said:

Physics is not a problem. I have a couple of qualifications there... ;) It's having to back calculate all of the manufacturer supplied data to find their definition of an apple and seeing what simplifying assumptions the tests allow/force them to make that's annoying.  For instance SAP ratings aren't really helping at the end of the scale I (and others here) want to work to.

 

Well I am different from most on here, I don’t have any qualifications, I didn’t do a passive house spreadsheet thingy, frankly I didn’t do any calculations at all, perhaps I am lucky but I just went with what I thought was right. (Sucks finger and sticks it in the air ?). What I did do was listen to everyone on this forum, particularly @JSHarris who has done a wonderful blog, I even went to visit his build to see it in the flesh. @SteamyTea told me of a chap in Cornwall who built his passive type house by going with his gut instinct and it turned out really well. Regarding my DHW tank I listened to the resident expert @Nickfromwales who even got a few of us a decent discount when we bought them. Yes it was a gamble, but I would not change anything apart from fine tune my MVHR and heating parameters to get better efficiency. (And I may go to E7 in the future).

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7 minutes ago, SteamyTea said:

Part of it is legislation.  We are told what we can and can't use and what quality standards to work to.

 

The only calculations that were done were by the architect (predicted SAP?) who listed materials and dimensions that I specified. Then the “as built SAP”, EPC, airtest and “U” values . All done by people that knew what they were doing (hopefully). None were done by me.

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43 minutes ago, SteamyTea said:

Part of it is legislation.  We are told what we can and can't use and what quality standards to work to.

I wonder how much actually gets enforced? ?

 

37 minutes ago, joe90 said:

 

The only calculations that were done were by the architect (predicted SAP?) who listed materials and dimensions that I specified. Then the “as built SAP”, EPC, airtest and “U” values . All done by people that knew what they were doing (hopefully). None were done by me.

Did your BCO ask for ( G3 ) certification for your UVC install?

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Just now, Nickfromwales said:

Did your BCO ask for ( G3 ) certification for your UVC install?

 

No, plumber forgot to give me one and he is on holiday so I am just going to see if the BCO spots it ?

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Just now, Nickfromwales said:

The aforementioned legislation may still kick your arse then :D 

 

Will just have to wait till said plumber returns to supply it ? BCO didn’t mention it on his final walk round, I just supplied certs fir what he asked for ?

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3 minutes ago, Nickfromwales said:

I wonder how much actually gets enforced?

Bit of a different issue.

But I think most BCO would spot the difference between bricks and cardboard.

They also rely on the integrity of professional bodies and leave it up to the owner/builder to sue for damages.

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I have a thermal store and once all the connections where lagged it doesn't lose that much heat over a day. Although before I done all that work out was really really warm in the hotpress. Through trail and error I got to the point where my sweet spot temp of the stored water is 67 degrees. It's just a balancing act from either a few degrees hotter and my stove will be on longer so burn more fuel or a few degrees lower and it will go cooler quicker and I get nailed by the wife for her shower going cold. 

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