Auto by-pass on regular boiler

[CMairiD]

If you have fitted an auto by-pass on a regular boiler (WB 18Ri), then is there any reason why an installer should be using a rad as a by-pass as well?

 

[diesel_ltd]

is your room stat in the same room as the rad your installer is using as a by-pass??

 

[wheeto]

If the rad's in the correct room then yes. Otherwise the rad stat could be set lower than the room stat, and the boiler would run constantly for CH.

 

[CMairiD]

Yes, kinda. Rad at bottom of stairs, no TRV. RF stat 1/3 way up stairway.

Tenants leave programmer on constant hot water only, but this single hallway rad is heating up.

 

[diesel_ltd]

the rad stat could be set lower than the room stat, and the boiler would run constantly for CH.

agreed with above

if on hot water only no rads should heat up

sound like your return from that rads is teed in the after the return from the cylinder on the return to the boiler and the rad is back heating on itself

 

[CMairiD]

Thanks for that!

 

[wnjswozo]

usaully leave bathroom rad as bypass,even with auto by pass

 

[wheeto]

usaully leave bathroom rad as bypass,even with auto by pass

Why...?

 

[CMairiD]

Yes, why?

I've just paid to have the system upgraded, including controls to make it more energy efficient. Assuming the bypass has been fitted, why would we allow a single rad to continue to chuck out heat when the programmer isn't calling for it?

I know that some of our older properties that haven't been upgraded do work like this (bathroom as a bypass). But if I've just paid to upgrade the system, it is my assumption it would be upgraded to eliminate this issue.

If my thinking is wrong, I'd just like to understand why it has to be left like that.

 

[GrahamM]

Yes, why?

I've just paid to have the system upgraded, including controls to make it more energy efficient. Assuming the bypass has been fitted, why would we allow a single rad to continue to chuck out heat when the programmer isn't calling for it?

I know that some of our older properties that haven't been upgraded do work like this (bathroom as a bypass). But if I've just paid to upgrade the system, it is my assumption it would be upgraded to eliminate this issue.

If my thinking is wrong, I'd just like to understand why it has to be left like that.

You are correct. Why put in a rad. bypass if an auto bypass is fitted?
Energy efficiency goes right out the window here.

If rads. heating when no call for heat then check out the zone valves. Heating side may be sticking open.

 

[diesel_ltd]

you need to leave the TRV off the rad in the same room as the room thermostat because if the rad trv cuts off before the room thermostat your heating system will continue to run until it cuts out on the boiler stat, hope this clears this up a bit for yous

 

[CMairiD]

Yep, all clear now. Thank you very much for the explanations!

 

[kirkgas]

surely if the programmer is on constant hot water the heating cant come on till the stat is turned up, nothing to do with one rad not having a trv, check out the old honeywell "3 T's" rule about where the pipework connections should be made in relation to each other, its a very common prob on old sysytems where the cylinder is in the bedroom cupboard with the water return and heating return connected together under the bedroom floor so when the water circulates round the cylinder it heats the bedroom rad flowing back up the return, check out the rad that is heating to see if it heats on the return first

 

[diesel_ltd]

If the trv cuts the rad off in the room that the room stat is in the then the room will not heat up to control the room stat correctly

 

[stevetheplumber]

the stat controlled area should not have a trv fitted, the stat is there to stop the boiler firing on heating even if all trvs are shut if you have a rad getting hot even with clock and stat not calling the rads are piped wrong