Boiler Frost Stat causing problems

[stem]

Good question. Either a Gas Safe engineer who understands how heating systems are wired (not all do) or an electrician that understands how heating systems work (not all do)

Basically the frost thermostat should by-pass the heating time control and the room thermostat, thus directly controlling the motorised valve. The motorised valve will then operate the boiler as it does in normal operation.

The Frost thermostat should ideally be wired in series with a pipe thermostat set at about 30 degrees C on the return pipe to the boiler. This keeps the pipes warm to stop freezing but also stops the property from overheating. You don't mention whether you have a pipe stat or not, but they usually come as a kit.

 

[Wildcat1961]

You don't mention whether you have a pipe stat or not, but they usually come as a kit.

Purchased many frost stats coupled with pipe stats over the last 35 of years, I’m not aware that these were/are sold as a kit?

 

[stem]

All Honeywell but here are some kit examples:

BES

ebay (check the price though )

RS

Plumbnation

 

[Wildcat1961]

Thanks Stem.
What would be your line of work if you don’t mind me asking?
Would it be controls wiring? If so how long have you been in the trade?
Thanks in advance.

 

[stem]

I did an apprenticeship as an electrical engineer back in the early 1980's, Today I produce specifications / designs / costings for control panels for factories that generally involve mixing / weighing & conveying of powders and /or liquids. Typically making plastics, bread, biscuits, plaster, cement etc. Wiring and circuits are generally my thing, so I don't get involved in the SCADA software part .

My involvement with heating systems initially came through my father who was a plumber (now deceased unfortunately ) and a couple of friends who are Gas Safe engineers that I help out from time to time when they get stuck fault finding or with a tricky controls installation.

I started reading / posting on this forum as I travel quite a bit, and had time to kill in airports, hotels, exhibitions and when I am overseas in Asia & the USA, jet lagged and can't sleep. Probably a bit risky giving wiring advice in that state though.....

Anyway that's me. Bet, you wished you hadn't asked now.....

 

[john306]

I'll do some ringing around this coming week to try to find someone who is clued up on both Electric controls and/or Gas.
There is the frost stat on my boiler but definately not a pipe stat.
Thanks

 

[Gasguru]

As mentioned before there should be a pipe stat clipped to the boiler RETURN pipe...this will shut off the boiler once the return water is at a sufficient temperature.

On the Hxi there MUST be a bypass valve..preferably an auto bypass (set at say 1 or 2 meters) to allow...

Sufficient water through the boiler when the radiators/cylinder is heated.

A flow path when the zone valves are both shut and the pump is on overrun.

A flow path when the frost stat is in operation...the bypass being installed in a position to allow all the vulnerable pipe work to be protected.

 

[john306]

As mentioned before there should be a pipe stat clipped to the boiler RETURN pipe...this will shut off the boiler once the return water is at a sufficient temperature.

On the Hxi there MUST be a bypass valve..preferably an auto bypass (set at say 1 or 2 meters) to allow...

Sufficient water through the boiler when the radiators/cylinder is heated.

A flow path when the zone valves are both shut and the pump is on overrun.

A flow path when the frost stat is in operation...the bypass being installed in a position to allow all the vulnerable pipe work to be protected.

Thank you, there is a mass of pipework, valves and pump in the airing cupboard, presumably a bypass too as when boiler is working normally everything is fine it's only when frost stat kicks in there's a problem. Although doing what stem said and manually opening heating valve before I manually activated the frost stat, cured the problem.
So I need to find why when the frost stat operates there is no flow.
Is there any other tests I may be able to do to narrow it down?

 

[john306]

Thought I'd do a follow up post.
I removed the Taconova setter bypass thinking that could be the only problem, and it was totally blocked of crud allowing no flow through it whatsoever..
Cleaned it all out, reinstalled and all working perfectly again.
Thanks for replies.