Thermal stores and all that

[John Rumm]

Got a scanner and some OCR? If so google translate will probably give you a bit of a clue as to what is going on...

[Jonathan]

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\

=A0 =A0 =A0 =A0|

=A0 =A0 =A0 =A0|

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D/

Good idea thanks Jonathan

[Dave Liquorice]

The water isn't circulated when there isn't suffcient heat to shift. The differential controller takes care of that, the circulation pump doesn't run until the panel manifold is a few degrees above the bottom of the solar tank/thermal store.

Also without water in the manifold you aren't going to know if the tubes are producing any heat. Our panel isn't doing anything most days ATM but if it's a bright day it will get up to 40C and yesterday I think it got hot enough to trigger the pump for a while as the recorded max panel temp was 90C.

As the pump only runs when there is heat to shift why bother with a drain back? Some differential controlers have a frost protection mode that runs the pump to warm the manifold from the store if it gets too cold. This is useful in places where frost is rare and "wasting" a bit of heat is cheaper than glycol. Not so good for the UK...

[Jules Richardson]

Although they are on his shoulders.

[Jules Richardson]

Although they are on his shoulders.

[Jules Richardson]

Although they are on his shoulders.

[Doctor Drivel]

I just had a thermal store fitted in a house. The house was two floors with a basement. Boiler and T-Store in basement. Customer wanted a simple reliable system. He wanted a gravity system as once he had gravity heating and DHW in a house - very simple with few parts. He asked if that is still possible with new condensing boilers. I said yes in his circumstances to his surprise.

The T-Store and boiler are below the ground and first floors - ideal for gravity. Two zones were taken off the store using 28mm and then 22mm to all rads with tee-off to rads 15mm. Bends used and Elbows to a minimum. TRVs on all rads. No pump used only two "motor on, motor off" 2-port zone valves for each zone (mo-mo valves), so no electricity is used when heating once the store is up to temperature. Both CH zones are fed via gravity from the store. A little slow in initial heat up for CH but fast enough - time the start up accordingly. A condensing boiler heats the store which uses a DHW coil not a plate as he wanted simplicity. This also maintains cylinder stratification

The only complexity is the two cylinder stats and the small latching relay and the self-contained boiler controls themselves. A simple, reliable Intergas open vented, condensing boiler was used to heat the store.

He took it under the deal that if the gravity circulation did not operate fast enough a pump would be installed. No need for the pump. So no noise in operation either. Also full electric backup for CH & DHW if needed.

The T-Store acts like an old large cast iron boiler, which had a very high water content and operated much like small T-Stores.

[Doctorr Drivel]

I yesterday visited the house with the gravity CH. Some Points:

- A advantage of thermal stores is that the rads are hot in a few minutes on start up as the pump pumps all the hot water to rads instantly. With gravity CH off the store this was not going to be the case. The warm up time is about the same, or slightly longer, as a perfectly matched CH boiler to the house directly heating rads from cold. So not a problem in warm up time.

- A disadvantage in thermal stores (which can be got around easily), is that when CH is called and working up to temp, and a large bath is drawn off the store cools. Then a slug of cold water is pumped to the rads. Usually this is not a problem as the store reheats quite quickly and recovers quick enough as the hot water in the rads is pumped back to the store aiding the reheat. When a large bath is drawn off and the store cools off, the gravity stops working, or slows up quickly, so naturally and automatically throttles back with no slug of cold water being pumped to the CH circuits - and no electronics to do it, which costs to buy and may fail in future and adds complexity.