unvented hot water cylinder

[ditchcrawler]

Hello. Yes, I meant that the cylinder is unvented. The heating part of it is but the cylinder isn't. My engineer said it needs to be vented, which isn't easy, or the cylinder be fitted with some sort of heat sensor pressure relief valve, as I understand it. He isn't a boaty plumber but an excellant domestic heating engineer. He said there is a way to do it safely that does comply with regs. He will get back to me when he finds out. In the meantime if anyone else can help I would appreciate it. Many thanks Steve P.

I would suggest that 90%+ cylinders are not vented on boats and 90% in houses are. I think the water being to hot is a red herring

[canals are us?]

now the rads are added and a drawing I can see no reason that it shouldn't work safely, but do you always want the rads to heat? what happens if both rads are switched off and the valve closes? you would then get "pumping over" into the header not a good idea! rethink the circuit design slightly and incorporate a loop at the other end of the circuit after the rads.

 

Yes the rads would need to be left permanently on with a solid fuel stove or at least one large double rad plumbed permanently on ie lockshield valves. In my gravity system layout above there is no pump used so no chance of pumping over. I personally would only light the stove when I wanted heat. I would just use the calorifiers immersion etc when the stove isn't lit.

 

Fudd, what I would do is still fit a small single gravity radiator near the stove and the 12 volt pump should effectively cool the gravity rad anyway and send the heat to the other radiator. My gravity rad on our solid fuel boiler gets very hot until the pipe thermostat triggers the pump and then the gravity rad only gets luke warm. Your plumber will advice if having the 12 volt pump is adequate and if you need a gravity rad. My only worry is if you had battery/controller problems.

I was thinking something like this thats pumped by 12 volt but still is open vented with gravity single radiator. I dont know if you want the stove to heat the rads in combination with another boiler? Your plumber will work this out.

 

 

Edited April 3, 2012 by canals are us?

[the grinch]

In my gravity system layout above there is no pump used so no chance of pumping over.

 

actually yes it would it doesn't need the pump as gravity water will still rise. the solution is to combine the cold feed and open vent into a single 22mm pipe.

Edited April 3, 2012 by hamsterfan

[canals are us?]

actually yes it would it doesn't need the pump as gravity water will still rise. the solution is to combine the cold feed and open vent into a single 22mm pipe.

 

Gravity water will only rise if it can complete a circuit to rise too. The loop is broken by the tank. I don't think it could boil over as the hot water has circulation through the rads. Single feed and vent pipes are an old design or used where pumps have been placed in the wrong location as a way to cure pumping over. Anyway the drawing wasn't all my layout so I would place the cold feed and expansion tank differently. I'll let the plumber fitting the stove decide as it's him who has got to be satisfied and I feel I'm now taking this off topic.

Edited April 3, 2012 by canals are us?