Thermal store wiring

[Scott_boy]

Hi guys. I'm needing a bit of help. I was helping a guy fit a thermal store tank in his house for his heating. He has two wood burners connected to it. As far as I know the wood burners heat the mass of water in the tank but its actually a coil that runs through the tank at cold mains pressure to supply the domestic hot water rather than the actual water in the tank. Anyway, I wired two immersion heaters to it and a tank stat which runs the heating pump. He is just about to move into the house so hasn't yet used the heating system as there is still a few bits of plumbing to be done.
Anyway, the problem is that we are scratching our heads as we are wondering if he puts on the water heaters to heat water for his taps, will this not just activate tank stat and pump water round rads and leave no hot water for taps? In fact, we are wondering how this tank can actually hold hot water without putting pump on therefore never having domestic water available? Can anyone explain this?

 

[Sintra]

Is there a 2 port valve installed to the ch pipe work? This could be controlled by a room stat and the tank stat in series.

 

[Scott_boy]

Hey, thanks for the quick reply. No there is not a valve fitted. That's why we are scratching our heads as we need to meet with the plumber to see why there is no valves. Would you suggest fitting one?

 

[Sintra]

Yes it sounds the simplest way. Room stat and tank stat in series opening the 2 port. In turn energising the pump.

 

[Scott_boy]

Ok, I'm a wee bit lost!! If he then puts on his immersion heaters to heat his tank for tap water and say if his rooms were cold would the room stat not call for heat and then the tank stat would call when immersion heated the tank and then the pump would fire?

 

[Sintra]

Hi guys. I'm needing a bit of help. I was helping a guy fit a thermal store tank in his house for his heating. He has two wood burners connected to it. As far as I know the wood burners heat the mass of water in the tank but its actually a coil that runs through the tank at cold mains pressure to supply the domestic hot water rather than the actual water in the tank. Anyway, I wired two immersion heaters to it and a tank stat which runs the heating pump. He is just about to move into the house so hasn't yet used the heating system as there is still a few bits of plumbing to be done.
Anyway, the problem is that we are scratching our heads as we are wondering if he puts on the water heaters to heat water for his taps, will this not just activate tank stat and pump water round rads and leave no hot water for taps? In fact, we are wondering how this tank can actually hold hot water without putting pump on therefore never having domestic water available? Can anyone explain this?

Ok, I'm a wee bit lost!! If he then puts on his immersion heaters to heat his tank for tap water and say if his rooms were cold would the room stat not call for heat and then the tank stat would call when immersion heated the tank and then the pump would fire?

Im also confused.

Are you sure? As far as I know it's the coil that is connected to the heat source that heats the cylinder not the other way round.

 

[Scott_boy]

Well I'm not 100% sure as I don't understand it. I see what you mean though. I think the hot water taps are on a coil anyway, which ain't the way I normally thought it would be. If the hot taps ARE on a coil and the burners on another coil will tank stat not still put on pump and start to circulate water in the radiator coil which would start to cool water in the tank. And then when you run the hot tap the coil would be sitting at same temp as the mass of water in tank which is already cooling?

 

[Sintra]

Normally a tank stat is for the dhw switching the boiler on or off as the cylinder temp drops and rises. As your heat source is a wood burner this tank stat might be used to divert the hot water to the ch system when the cylinder reaches temperature. Without seeing the set up its hard to tell.

 

[Scott_boy]

Well it's a thermal heat store tank and it says it works in reverse of most conventional tanks with the hot taps running through a coil which is fed from the cold main and it heats when it passes through the mass of water. Like you suggested the burners run through a coil in the tank to. I read something about the water in the tank doesn't change or get pumped, it just sits there and heats up and cools down all the time. Anyway, I think we will just have to see how it works when we fire it up.

 

[Sintra]

Think i get what it is now after a quick look on google lol. It seems to be made up of heat exchangers for the dhw and ch. no point me trying to comment any more on this type of system as I have never experienced one of them

 

[davethsparky]

I've played this game before with the amazing gledhill boilermate thermal store.

Don't know about your particular model but the basic theory is:

Insulated Tank full of water.

1/2 immersions in the tank

Pipe connections to the tank running to the other heat sources (boiler/wood burner) with a pump.

A heat exchanger which has hot water from the tank pumped through it, cold mains is fed to the other side of the heat exchanger and hey-presto hot water at mains pressure.

Coil in the tank with a pump is connected to the central heating system and acts like a standard cylinder in reverse.

So no need for valves as you have a seperate pump for each bit.

Tank stat operates boiler or whatever and a pump to heat the stored water.

Hot water heat exchanger stat maintains the hot water supply at a set temperature by operating the associated pump.

Central heating controls operate the pump in the coil/heating pipework.

Simple eh?

 

[Dcf]

You will probably need hi/low limit pipe stats if wood burners are used as they can get really hot.
The heat source be it wood burner /boiler/heat pump/solar is only concerned with keeping the water hot in the tank.
as Dave says then the controls for heating and hot water bring on pumps to circulate round the heating etc
its a bit of a mare to get your head around tbh

 

[snowhead]

Im also confused.

Are you sure? As far as I know it's the coil that is connected to the heat source that heats the cylinder not the other way round.

Ignore this,
answer already covered above by others

 

[davethsparky]

More than abit of a mare when you have to try and educate the plumber who's replaceing the boiler feeding one of these. Poor sod was amazed at how quickly the powerflush ran clean without realising he'd only been flushing the coil that heats the thermal store!