Piping query

[EFLImpudence]

Maybe it's a deliberate thermosyphon to radiate more heat into the airing cupboard when you want to dry some clothes?

It's hot enough in there already - especially when working in there.

You have to leave the door open.

 

[JohnW2]

Yes, the only advantage I can think of is less heat loss on the return to the boiler.

...and, as mfarrow has said, greater boiler efficiency if the return temp is lower (achieved by lower flow rate).

In terms of what you say, we have a cunning arrangement which prevents most of that 'heat loss on the return to the boiler' being wasted - nearly all the length of that pipe is routed through a separate airing cupboard on the floor below, which is keeps reasonably warm!

Kind Regards, John

 

[EFLImpudence]

A cunning plan, indeed.

I assume the locations are close, not that W2 Towers has an airing cupboard the same size as the little house in my picture.

 

[JohnW2]

A cunning plan, indeed. I assume the locations are close, not that W2 Towers has an airing cupboard the same size as the little house in my picture.

Yes, very close. It was purely fortuitous. There was a small cupboard, adjacent to the utility room, vertically below the 1st floor airing cuboard (with cylinder) and, in fact, through the cupboard was about the only sensible route for pipes to/from the cylinder down to the boiler. When we realised how warm the pipes were making the downstairs cupboard, we decided to redfine it as an 'airing cupboard', particularly since it was strategically placed close to washing machine and dryer. In fact, it's not only the pipes to the DHW coil - the CH pipes for upstairs also go through the cupboard.

Kind Regards, John

 

[ScottishGasMan]

Bypass pipe is purely that, so if the circuit the pump is feeding closes the pump still has a path to push water round to prevent overheating in the boiler.

The reason you would fit on even tho you have a 3-port valve (thus always having an open path) is if you had thermostatic radiator valves, so when 3-port is on heating only mode, and your rooms got warm and all TRVs were to close off at same time then there is still a loop.

If you dont have thermostatic rad valves, or you have one or two radiators that dont have them and are always kept open at the valves, then you can close bypass as its of no use. If you do have TRVs, then bypass should be opened, normally between a half turn and 2 turns depending on valve.

 

[EFLImpudence]

But it is on the DHW pipe only bypassing the cylinder coil and hence not accessible when DHW not called for or satisfied.

 

[JohnW2]

Bypass pipe is purely that, so if the circuit the pump is feeding closes the pump still has a path to push water round to prevent overheating in the boiler.

It's only 'bypassing' the coil in the cylinder - the coil surely provides a path for the pump to push water through?!

Kind Regards, John

 

[ScottishGasMan]

Then its fitted wrong. Not the first time I would have seen a plumber put a bypass in the wrong place. Theres no need to have it open with regards to altering flow through the cylinder or for potential blockage in future. There only purpose is ever to allow a flow through pump when there are valves on system that can close automatically to prevent pump flowing water.

Only other time you will sometimes see a gate valve on flow or return to cylinder is to restrict flow through it to encourage water flow more evenly through radiators rather than taking easy route round cylinder.

The set up you have, I have never seen, and don't belive its fitted correctly, cant see any good reason for doing it that way

 

[JohnW2]

Then its fitted wrong. ...The set up you have, I have never seen, and don't belive its fitted correctly, cant see any good reason for doing it that way

Exactly. That's why EFLI posted the question (with a photo), because that's what he believed (and so did I - although I did also try to think of some way-out possibilities asto why someone might have thought it was a good idea!).

Kind Regards, John

 

[ScottishGasMan]

Lol, Nope, can't think of any good reason for that. (not on a cylinder anyway, some old systems would have that between flow/return to individual radiators)

If its closed and working just leave it as it is.

 

[ricicle]

Most pump bypasses I see have pilot valves on them which only open when the pressure increases above a set threshold.

 

[JohnW2]

Most pump bypasses I see have pilot valves on them which only open when the pressure increases above a set threshold.

Indeed. If it's there just as a 'safety' measure (pressure limiter), they usually are - to have a constantly open bypass would presumably be wasteful/innefficient. However, if one were using a bypass for a 'control' measure (e.g. per ScottishGasMan's last post), then it would have a manual control.

Kind Regards, John