Heat acumulator tank on rayburn?

[Tom D]

The boiler is a condensing conventional one, not a combi, The system works well, I have the stat on the gas boiler set low so as soon as the stoves kick in the boiler stops heating.

We use about 400l of gas every 18 months.

[Stereo]

I've just been looking at the installation done on our tank and I'm thinking our plumber has got it wrong based on something Catweazel said earlier. This is our tank (picture on page 7)

 

http://www.plumbnation.co.uk/site/gledhill-torrent-re-solar-vented-mains-pressure-foam-lagged-copper-thermal-store-cylinder/gledhill-torrent-re-solar-installation-guide.pdf

 

He has connected the return to the stove correctly (bottom 28mm connection) but he connected the hot flow from the Esse to the 28mm boiler return half way up the tank, not the one at the top marked 28mm alternative energy flow.

 

So the hot flow from the Esse is going in halfway up the tank, not into the top. Anyone think this might be a problem?

 

I'm pretty hacked off with the job they did really. I don't think the flue they did for the Esse is good either (too much enamel and not enough SS and I can't sweep it without getting on the roof). Plus he bodged the boiler connections on the tank.

[openspaceman]

He has connected the return to the stove correctly (bottom 28mm connection) but he connected the hot flow from the Esse to the 28mm boiler return half way up the tank, not the one at the top marked 28mm alternative energy flow.

 

So the hot flow from the Esse is going in halfway up the tank, not into the top. Anyone think this might be a problem?

 

I doubt it will be a problem, the systems I worked on used solar thermal to heat the top of the tank for DHW so it was important to keep the top of the tank as hot as possible with the little contribution available, so the last this you want is to allow it to diffuse up through less warm water. I imagine the heat input from your boiler is significant compared with the size of tank. Ours was at best 25kW(t) into a 3 tonne tank. In the event they plumbed the underfloor system in wrongly and quickly destroyed the stratification, problem was compounded by having the DHW plate heat exchanger pumps only set to trigger as long as the top of the tank was above 50C, leaving 12 flats with no DHW. Housing association staff were the dumbest set of jobsworths I ever came across, no concern for their tenants.

[Stereo]

I though it was all about stratification or some such? I'm looking at a Laddomat as well but apparently they need to be near the stove which may cause us some problems with pipe runs. Also they need a short run to the tank and ours may be marginal I think.

[openspaceman]

I though it was all about stratification or some such? I'm looking at a Laddomat as well but apparently they need to be near the stove which may cause us some problems with pipe runs. Also they need a short run to the tank and ours may be marginal I think.

 

It is about stratification, keeping a hot body of water sitting on top of the unheated water underneath. Water is a poor conductor and as hot water is lighter than cold ( until 4C) there is little heat transfer from top down.

 

If you introduce hot water at the middle of the tank it rises through any cool water above it and mixes as it does so, producing a layer of warm water at the top. If you introduce the hot water at or near the top there is less opportunity for mixing and the top remains available to draw off as hot water from the top.

[Stereo]

Thanks.