Could heating systems be improved with this idea?

[vexation]

While trying to figure out the cause of my central heating woes I'm wondering if there's a useful improvement that could be made to the current type of system:

Having TRV's is clearly a good idea: All radiators should have them fitted to allow individual rooms to be set to a preferred temperature. But something needs to tell the boiler whether or not there's a demand for heat. Traditionally this is done with one or more room-stats.

In the UK, Eaga (the independent Partnership Charitable Trust for the promotion of energy efficiency) advise having no TRV in the room with the overall thermostatic control. This room then dictates the boiler demand. With this setup, this room may then have to be run at a higher temperature than is desirable in order to keep sufficient heat to meet the demand in other rooms. In my own case the thermostat controlling the boiler is in a large hallway that extends all the way up to the V of the roof. Naturally the radiator in this hallway just sends heat up to the top where it gathers in great quantity!

So, when all the TRV's close, this unregulated radiator in the hallway is all the pump/boiler has to feed and I can almost sense the "tension" building up before the room-stat trips. But this got me thinking: the signal that the boiler is no longer required could be that *all* the TRVs have closed...

...So if the pressure in the system (or would it be flow rate?) is set to cut the boiler in/out at a certain threshold, then *all* rads can have TRV's and the boler is only called on when one or more TRVs requires it. Perhaps I'm talking nonsense, perhaps this has already been done (where can I buy one?) or perhaps it will make me rich

Er, perhaps not now I've mentioned it [/i]

 

[DCC]

I think you can have all rad's with TRVs if you have a bypass of some sort (don't quote me I'm not a professional) - It's not perfect as you'd be still heating the water in the pipes but better than nothing.

 

[JohnD]

... this room may then have to be run at a higher temperature than is desirable in order to keep sufficient heat to meet the demand in other rooms. In my own case the thermostat controlling the boiler is in a large hallway that extends all the way up to the V of the roof. Naturally the radiator in this hallway just sends heat up to the top where it gathers in great quantity!

so why not turn down the lockshield?

 

[malkie]

thats why boilers have t/stats on so you can have it to go off on a lower temp and boilers have built in by passes now so its not the norm now to leave a rad without a trv on

 

[vexation]

I think you can have all rad's with TRVs if you have a bypass of some sort (don't quote me I'm not a professional) - It's not perfect as you'd be still heating the water in the pipes but better than nothing.

Yes, there are automatic bypasses that open when everything else is shut - but then its far from perfect to have the boiler on for nothing. If the roomstat is set to a higher temp than will ever be reached this could be for hours each day... malkie, that surely applies to the kind of boiler you mention with a built-in bypass?

 

[fitz1]

if all rads have trvs and an auto bypass is fitted , why cant we discard the roomstat.

 

[JohnD]

that would be a great idea if you wanted to keep the boiler running all the time, like a very expensive radiator.

But why would you want that?

 

[snb]

because the part L building regs require boiler interlock. a room stat is one way of achieving this.

 

[vexation]

... this room may then have to be run at a higher temperature than is desirable in order to keep sufficient heat to meet the demand in other rooms. In my own case the thermostat controlling the boiler is in a large hallway that extends all the way up to the V of the roof. Naturally the radiator in this hallway just sends heat up to the top where it gathers in great quantity!

so why not turn down the lockshield?

You're right: In theory I could do, and lower the room-stat accordingly, but I tried this and when the last TRV closed the boiler would sometimes go over 105 deg. which I assume (judging by the noises) is bad. Without bypassing this just doesn't work in practice, and with bypassing it still leaves the whole house at the mercy of the hallway.

 

[JohnD]

... the boiler would sometimes go over 105 deg...

Faulty boiler stat.

 

[vexation]

that would be a great idea if you wanted to keep the boiler running all the time, like a very expensive radiator.

But why would you want that?

Exactly. So why not have the auto bypass (wherever it is) also cut the boiler? The pump would remain on (as per room-stat control) so as TRVs open the bypass shuts off and the boiler fires up (as per my patented inverntion )

 

[JohnD]

. So why not have the auto bypass (wherever it is) also cut the boiler? The pump would remain on (as per room-stat control)

Boiler stat will stop the boiler firing when it reaches temp (except that yours sounds to be faulty)

And when the room stat is satisfied it will tell the boiler to stop firing.

I don't see what the problem is that you are trying to invent a solution to.

 

[vexation]

... the boiler would sometimes go over 105 deg...

Faulty boiler stat.

I don't think so. It's a brand-new boiler set to 85, and it cuts out at 85. I'm guessing the (very) short circuit left once the last TRV shut off gave a rapid rise over residual heat in the heat exchanger. It only went up to 105 very briefly, but that's no good.

 

[JohnD]

85

why doesn't you last remaining rad,in the hall, sink the heat away? Have you got a TRV on that too? Set colder than the room stat?

 

[vexation]

Boiler stat will stop the boiler firing when it reaches temp (except that yours sounds to be faulty)

And when the room stat is satisfied it will tell the boiler to stop firing.

I don't see what the problem is that you are trying to invent a solution to.

JohnD, please bear in mind that I'm an electronics engineer not a plumbing engineer so I do expect to be corrected

I think you'd agree though that a satisfied room stat does not necessarily indicate that all rooms are satisfied. In an attempt to ensure this, it would seem to be necessary to identify the last room to reach it's desired comfort temperature before the stat is fitted in that room.

I would prefer to see a democracy where the vote of every TRV counts equally rather than be subject to the tyranny of a single dictator