Frost Stat Problems

[B1lly123]

Hi

Moved into a new build a few months back and have a Logic 18 boiler situated in the garage with a Honeywell Frost Stat and Pipe stat. Heating is a two zone system - one for downstairs and one for upstairs.

Frost stat is set at 4 degrees and pipe stat is set to 10 degrees...my problem is that on cold days:

- the frost stat kicks in and switches the boiler on

- boiler runs for 10-15 minutes, during which time the downstairs radiators become boiling hot

- pipe stat then kicks in and switches the boiler off...but the frost stat typically kicks in 30 minutes later and the cycle continues

It was ridiculous yesterday as downstairs got up to around 25 degrees due to this vicious cycle and the place was sweltering.

When I went out to check the boiler, it was fired up with a C symbol on the display...when I checked the manual this suggests it's the central heating calling for the boiler to fire up rather than the frost stat (should be a F on the display) but neither of the programmers were calling for heat as I had deliberately switched them off.

I am convinced they have wired up the frost stat/pipe stat wrongly and that when it's kicking in it is wrongly calling for the heating to switch on rather than getting the boiler pump to kick in and do a quick heat and circulation of water to get the pipes up to temp...anyone else came across this issue before? The builders have been out a few times now and their only advice is to turn all of the downstairs radiator TRV's to the zero setting to help manage the temp spikes

 

[FlyingFish]

It's probably just because the installer has fitted external frost protection, when actually the boiler has its own. And if it's wired correctly with its own permanent live, pump live, and switch live. Then there shouldn't be any need for anything external, unless for any other reason. Like not just the boiler in a vulnerable location.

Oh just thought, if you have a zoned system, then it 'should' be something like an S-plan plus. If that's the case, the external frost protection should run through a bypass and not heat a radiator zone up. Unless it's been specifically designed to do a certain protection job, not just the boiler.

 

[B1lly123]

It's probably just because the installer has fitted external frost protection, when actually the boiler has its own. And if it's wired correctly with its own permanent live, pump live, and switch live. Then there shouldn't be any need for anything external, unless for any other reason. Like not just the boiler in a vulnerable location.

Oh just thought, if you have a zoned system, then it 'should' be something like an S-plan plus. If that's the case, the external frost protection should run through a bypass and not heat a radiator zone up. Unless it's been specifically designed to do a certain protection job, not just the boiler.

Thanks for the quick response - builder is back out this week so will ask them around reason for external frost stat when the boiler comes with one built in. Assume from your response that it's not normal for the radiators to be heating up because the frost stat has come on?

 

[FlyingFish]

It all depends how the system has been designed. I'm only guessing it's something like an S-plan, which should have a bypass, which is usually adequate for frost protection, unless other requirements need to be met.

 

[Steelmasons]

Possibly the pipe stat has been attached to the gas pipe.

 

[B1lly123]

Possibly the pipe stat has been attached to the gas pipe.

Just checked - thankfully not