What size boiler?

Slinky

I curse the day my husband was recommended to a Vaillant boiler. It has a setting on it that it doesn't appear you can change, that if the outside temperature reaches 5 degrees, it automatically comes on and heats water in your pipes to 30 degrees to stop them freezing. That's despite it being aware the internal house temperature may be 18 degrees or so. Our boiler is below our new master bedroom. This 'feature' means that I have been awake most of the night listening to the boiler coming on and off pointlessly heating our pipes, wasting gas and driving me insane. Tonight I will be moving back to our spare room, unable to use the master bedroom again until the spring.

Oh and the control panel is a source of argument between my husband and I twice a year, spring and autumn, when we struggle to work out what the 'features' do. Alright if you want heat and water on the starship enterprise. Way to complicated if you just want hot water and heating in an average home.

Avoid Vaillant - money wasting gas boilers.

macman

You should be able to disable/adjust the frost 'stat setting in the installer menu? All modern boilers have a frost 'stat built in.

Slinky

The bloke who installed it couldn't disable/adjust it! If there's somebody who has knowledge of how to override this on an EcoTec 624 you'd make a very tired and grumpy woman very happy.

macman

Have you looked in the installation and servicing manual which the installer will have left with you as part of the commissioning procedure? This should explain how to access the installer menu.
However, the frost 'stat will only be responding to a heating flow temp of less than 5C-nothing to do with the outside temp (which the boiler has no way of measuring, unless it's fitted with a weather optimiser). If your flow temp really has dropped as low as 5C, then something is clearly wrong, as the 'stat is kicking in to prevent it freezing. Just how cold is the room where the boiler is located?
If the temp is genuine, then it isn't 'wasting money', it's stopping the whole circuit freezing up. I would suspect that either the frost stat temp is set wrongly from the default, or that the sensor is faulty.
Either way, get the installer or Vaillant in under the warranty.

Slinky

The boiler is connected to a weather optimiser. I've had a look at the installation manual, but I'm not a technical person and it's a bit beyond me (I struggle to find how to override the timer just to turn the damned thing on!).

The boiler is in the garage, but it's a well insulated garage (only built 4 years ago) so I really don't believe it's getting that cold in there.

We're out of warranty now and the original installer (chosen by our builder) wasn't a Vaillant expert and couldn't work out how/if you can turn this feature off.

macman

OK, but AFAIK the frost 'stat still works based on the CH flow temp, not the external temp. All the optimiser does is turn on the CH earlier/later in order to get to the set temp by the programmed time-when the weather is colder it will switch on earlier. Are you sure it's the frost stat kicking in-if so it should display S.34 on the board?
I suggest that you need to monitor the garage temp for a few nights. Last night in the SE it got down to 3C, so 5C in a cold garage is not impossible.
Have you spoken to the installer or Vaillant to resolve the issue?

Slinky

I'm assuming it's the frost stat. There's no other reason why it would start kicking off randomly in the middle of the night. TBH I've not dragged myself down there to check what it's saying on the board at silly-o'clock in the morning. It fired for about 10 minutes at least 4 times overnight.

I've poked about on the net and found somebody else who has also mentioned this issue of it firing in the night

"1. The frost protection is very 'sensitive' so will fire in the middle of the night if the temperature drops to below 5 degrees. To stop it being so fussy, I have set the frost protection delay (LFOOh)to 12 hours, so it doesn't fire."

I'll get my husband to see if he can look at this as a possible solution.

Thank you for your suggestions macman

macman

You are approaching this from the wrong angle. Make the effort to establish the cause before you call anyone out. If it's waking you up anyway, how hard is it to go and look?
Then monitor the actual overnight temp in the garage.
Could it be the warm start hot water function running instead? If so, you can disable it.
If the temp is falling that low, then the frost stat is functioning correctly to prevent you having a very expensive failure. Altering that will simply remove that protection. It's not being 'fussy', it will start to freeze at about 3C.

Slinky

TBH if it is getting that cold in the garage (which I really do doubt, the walls are insulated as is the garage door), I'd rather put an oil filled radiator in there with a thermastat to warm the garage and protect the boiler than listen to the damned thing keeping me awake at night.

The point is though it wouldn't make any difference as far as the outside temperature is concerned, where the boiler was sited. It could be in our kitchen (location of previous boiler) and it would appear the system would still fire up if it gets to 5 degree outside.

macman

But it doesn't fire when it's 5C outside. According to the manual, it fires when the CH flow circuit drops to 5C.
The optimiser is a optional extra, so on most installs the boiler does not have a clue what the outside temp is. The frost 'stat still needs to be able to function without the optimiser being fitted.
Check the ambient overnight temp and then get the sensor inspected under warranty. From the manual, there is no way of altering the default 5C setting, so the sensor must be suspect if the temp is not dropping that low.
Heating the garage is not the solution.