Fine Tuning By Pass

[I am bonkers]

Wanting to be sure that the by pass on my S plan (2 heating zones and water) is balanced correctly. Recently had new boiler, now with over run on the pump. Old boiler didn't have this. All pipework the same as before. The by pass is 22mm pipe with gate valve. I am supposing that as long as the by pass runs cooler to touch than the primary circuit but heats up temporaily when all 3 valves close, as the over run kicks in, then it is correct. Would there be much of a detrimental effect on the system performance if the valve were to be open a bit too much? Better that than too far closed I guess?

 

[doitmyself]

Make and exact Model of new boiler, please.

 

[I am bonkers]

Make and exact Model of new boiler, please.

Worcester 24Ri. Thanks

 

[doitmyself]

Worcester 24Ri.

OK. That boiler does not have a built in by-pass.

Your installer should have changed the gate valve for an automatic bypass valve (ABV). The gate valve is permanently open, even if it's only a little bit. The ABV stays closed until zone valves or thermostatic rads valves start closing, it then opens to maintain the correct circulation through the boiler,

Ask your installer why he did not do this.

 

[Puddle]

OK. That boiler does not have a built in by-pass.

Your installer should have changed the gate valve for an automatic bypass valve (ABV). The gate valve is permanently open, even if it's only a little bit. The ABV stays closed until zone valves or thermostatic rads valves start closing, it then opens to maintain the correct circulation through the boiler,

Ask your installer why he did not do this.

Spot on

 

[I am bonkers]

OK. That boiler does not have a built in by-pass.

Your installer should have changed the gate valve for an automatic bypass valve (ABV). The gate valve is permanently open, even if it's only a little bit. The ABV stays closed until zone valves or thermostatic rads valves start closing, it then opens to maintain the correct circulation through the boiler,

Ask your installer why he did not do this.

Spot on

Thank you both. Before I approach the installer I'd just like to be sure of my facts.

The existing bypass may have been a correct method for my previous non-condensing boiler but is not suitable for continued use with the new Worcester 24Ri?

Would that be a fair assessment?

 

[doitmyself]

The existing bypass may have been a correct method for my previous non-condensing boiler but is not suitable for continued use with the new Worcester 24Ri?

Would that be a fair assessment?

Yes. In addition, the current Building Regulations and associated documents stipulate that, where a bypass is fitted, it must be an automatic type.

 

[I am bonkers]

Yes. In addition, the current Building Regulations and associated documents stipulate that, where a bypass is fitted, it must be an automatic type.

Thank you. That's very interesting!

Incidentally, what got me investigating in the first place is that zone 2 heating started coming on unrequested when either zone 1 or the water is switched on, regardless of its thermostat or controller settings. I am assuming that this is a faulty valve and that it is unrelated to the new installation. Would that be a fair assumption too? The system was flushed.

 

[doitmyself]

Incidentally, what got me investigating in the first place is that zone 2 heating started coming on unrequested when either zone 1 or the water is switched on, regardless of its thermostat or controller settings. I am assuming that this is a faulty valve and that it is unrelated to the new installation.

You said you have a S plan with two CH zones and a HW zone, so presumably you have three 2-port zone valves. Theses valves have 4 wires, brown, blue, grey and orange. The brown and blue are the motor connections, grey and orange are live and switched live to the boiler.

If you have a meter, you can check the valve is working properly.

Turn the programmer off and the thermostat down
Check 230v on grey only (boiler should not run)
If 230v on grey and orange, the switch contacts in the valve are stuck together.
Turn programmer on, leaving stat down
Check 230v on grey only (boiler should not run)
If 230v on brown as well, the thermostat contacts are stuck together
Turn stat up
Check 230v on brown, grey and orange (boiler should run).

If it passes all tests but the rads still heat up, the problem is due to the valve sticking open. Remove actuator anc check the valve spindle turns easily (about a quarter turn). WD40 or a silicon lubricant may help.