Any issues using pipe thermostat for pump overrun?

[MJA]

I recently helped a friend trace a central heating fault. The "wiring centre" was a mess. A single gang surface pattress covered with blanking plate and a mess of crimped connections inside made testing and replacement of components difficult.

We plan to fit a conventional wiring centre at some time. System is open vented Y-plan with an Ideal ICOS HE24 boiler fitted recently to replace previous boiler. Unusually for a modern boiler there is no pump overrun.

I was wondering if it is worth fitting a pipe thermostat to the flow to give pump overrun when replacing the wiring centre. Pump live would be fed from the thermostat common contact, thermostat normally closed to switched live, and thermostat normally open to permanent live.

Is there any point in bothering? Will it help boiler reliability? There are no signs of boiler kettling or overheat lockout occurring when call for heat is satisfied, but it seems a good thing to do if we are fitting a new wiring centre.

Is the temperature setting of the pipe thermostat critical? I am thinking:

1) if set too low, when call for hot water is satisfied the circulating pump will keep running and wastefully extract stored heat from the hot water cylinder, while on the other hand 2) if set too high, pump will never overrun when call for central heating is satisfied, particularly with a modern condensing boiler which is more efficient with a low temperature.

Is there any experience on the best setting for the pipe thermostat?

Regards,

MJA

[dennis]

If the boiler doesn't have an overrun stat why fit one? Its just more to go wrong later.

[ARWadsworth]

I would not bother if things are running OK. If you really did want a timer overun then a seperate timer set for say 3 minutes would be my prefered option eg

[Roger Mills]

But why worry about solving a problem you haven't got?!

[Michael Chare]

I use a flow switch to turn on my boiler. That way the boiler can't fire if there is no flow.

Perversely the switch failed, which had it happened early in out holiday could have led to the house freezing. The switch also started to leak though fortunately not enough to cause significant damage. The replacement is much less likely to leak as it does not have a flexible membrane!

[MJA]

mounting timers before, but using an extractor fan timer seems more cost effective.

The consensus is just to fit a standard wiring centre and not worry unless there are problems with the boiler kettling or going into overheat lockout when the call for heat is satisfied.

If it were my own heating system, I think I might try experiments, but as it is a friend's system I agree it should remain absolutely bog standard and cause no surprises for anyone who repairs it later.

Thanks for all the comments.

MJA