Intersting thermal store

[joe plumber]

Went to look at job today. It was an old thermal store usual set up one coil for dhw. And then another coil Which ran several underfloor manifolds. On the incoming cold into the dhw coil there was a flow switch which when drawing off hot water would overide the store stat and fire the boiler!! I'm pretty sure you can't do thAt?? It was also a unvented store!! Apparently according to the owner it was a old Nu heat system to go with there UF heating system. The rubber hose system that perished . Just curious to know if anyone else has come across this ?? I wouldn't be surprised to find it's a Bodge as the standard of the install was one of te worst I've ever seen. Anyway needless to say I'm ripping the whole lot out and reconfiguring.

 

[Gray0689]

You mean there was a coil for heating so it could be a sealed system that's fine
Don't know about the flow switch is not a good idea to bypass the stat

 

[joe plumber]

Yes as IMentioned the the lower coil was connected to several underfloor manifolds and was peessurised nothing unusual about that. My main concern was the flow switch which bypassed the stat controlling the primary water temp. The primary was also pressurised.

 

[Gray0689]

That would be an expensive thermal store cheaper to put in unvented cylinder and would be cheaper to run

 

[stevetheplumber]

youll probaly find theres only one coil for domestic in the top of the cylinder the heating is normally drawn of the tank direct
the flow switch tells the boiler to switch on and bypass the heating stat as it needs full boiler output to keep up with hot water demand in much the same way a combi goes to full fire for hot water
ive got a similar system in my house there are several advantages to heat stores
no blow out pipework to run
you dont need an unvented ticket to fit one
no reduction of preasure if your lucky enough to have a ten bar main you get ten bar hot water
no motorised valves
downside is
two pumps
its open vented

 

[Gray0689]

youll probaly find theres only one coil for domestic in the top of the cylinder the heating is normally drawn of the tank direct
the flow switch tells the boiler to switch on and bypass the heating stat as it needs full boiler output to keep up with hot water demand in much the same way a combi goes to full fire for hot water
ive got a similar system in my house there are several advantages to heat stores
no blow out pipework to run
you dont need an unvented ticket to fit one
no reduction of preasure if your lucky enough to have a ten bar main you get ten bar hot water
no motorised valves
downside is
two pumps
its open vented

That's good but only if no other heat source connected ie a multi fuel stove

 

[joe plumber]

Yeah that's pretty much what I had boiler straight to store then UF heating run of a coil the only space heating in the house. Like I said I'm familiar with concept of a thermal store just hadn't seen the flow switch before seemed a bit dubious to me. Any way it's all irelevant as I'm gonna rip the bugger out and out a 300l unvented in

 

[buckley plumb]

come across nu heat thermal stores in a block of 6 barn conversions last year very expensive set up especialy on lpg and the customers hated them. from what a remember these are just over a year old now and they worked similar to that . you can down load the manuals and wiring diagrams from nu heat web site.these were 300 litre cylinders running 5 uf manifolds and towel rails which were on the hw secondary rtn very unusual .they did my head in trying to sort the problems they had.

ant