Vaillant condensing boiler freezing - minimising condensate?

BooJewels

I'll return to all of your helpful posts shortly - I really must get the shower I didn't get yesterday morning as I have a phone appointment shortly - and I need to prep some notes first. 

I was heading for the shower and noticed the landing radiator I walked past wasn't as raging hot as it had been earlier - then heard the boiler gurgling again - it seems to reverb through the floor boards above it where I was walking.  It was indeed gurgling and the temp had dropped to 44°C.

So I've done the hot water routine again and taken photos, whilst I stood in the snow looking a right silly beggar in my snow boots, nightie and dressing gown and my gardening fleece and gloves.  It soon stopped gurgling and begun running smoothly again and within a few minutes the temp was up in the 60s again.

The outside temperature is now showing as just above freezing and was -3.1°C overnight - but that's on a wall, so I suspect air temp is a smidge lower.

I'll come back with photos later.  Very many thanks!

Edited later for a missed typo.

plumb1_2

Get some closed cell pipe insulation. 35x25mm wall 
specific for external condense pipe 

TimeLord1

Sounds like you need to bleed the radiators letting the excess air out now. Some are flat head screwdriver some are radiator keys. Bit of tissue 

https://youtu.be/0IP54Kbgnv0?si=NiG4AZc2MZF4lWul

ashe

We get this every year and it drives me potty 

our boiler is in the loft, handy as they are unsightly, but annoying for things like this. Was put there by previous owner. 

the condensate pipe comes down form the boiler and runs - almost flat- along loft boarding to the eaves and then out under a roof tile, to the gutter. 

It's not the best setup at all - the pipe ideally needs a better run with more fall, and they aren't meant to go into gutters at all because of the acidity mentioned in previous posts, but our loft has no waste pipes - our soil stack is internal and only comes halfway up our bathroom and is boxed in, so there isn't really anywhere to run it other than the gutter 

in at the point where I think doing much else with the pipe is probably pointless, and to investigate a trace heating kit to warm the condensate that does come out of it. The inside is lagged already but it's just the cheap foam, I'm going to buy some of the thicker closed cell stuff as that will hopefully do a better job. 

As it is, when it happens we either have to wait it out or pay our window cleaner to come and pour hot water on it. Interesting that the flow return temp may help though, i might have to try that. 

To the OP, just make sure it's warm water you use and not boiling as you can crack the pipe if it's temp changes too quickly. 


Can see here how it's frozen, probably just little bits at a time and gradually builds up 

Eldi_Dos

@ ashe

Could you instal a interception point on the pipe and use that to introduce a salt water solution into pipe, see if that works its way down and clears the ice blockage?

Albermarle

grumpy_codger said:

BooJewels said:

grumpy_codger said:

BooJewels said:

WIAWSNB said:

It can also be drained via your internal plastic waste - say kitchen undersink plumbing.

Bear in mind that condensate is slightly acidic, and will damage some surfaces such as masonry and metal - it'll eat through a copper pipe, for instance. 

If you can take a photo of the pipe tomorrow, that would be great - we can advise if lagging might help. It doesn't need to fully surround the pipe. The freezing is probably a borderline occurrence, so anything at all will likely sort it. 

It's too far from any internal waste pipes, on the opposite side of the house from all the plumbing, so I don't think that's a practical solution - I'd been thinking about that too - probably why it was done this way in the first instance.

A common solution, that personally I don't like, is a condensate pump with a flexible pipe/tube running through a loft to some internal waste pipe (or, possibly, a gutter downpipe in which case you have only a very short piece of pipe to insulate)

...
The very simplest solution is to insulate the 5' of condensate downpipe - so I'll post photos later.

If you mean using usual (grey) foam pipe insulation, beware that it's for internal use an deteriorates very fast under sunlight.

We have a ramp outside the front door with very low rails. We use this grey foam pipe insulation over the rails, so we do not bash the bottom of our car doors when we open them next to it.
It does deteriorate a bit - South East facing driveway so gets a lot of sun/heat in the Summer, but normally lasts a couple of years at least and only costs One to Two pounds a metre anyway.

ashe

Eldi_Dos said:

@ ashe

Could you instal a interception point on the pipe and use that to introduce a salt water solution into pipe, see if that works its way down and clears the ice blockage?

Potentially - i think I'll just get the trace heating thing done though as should hopefully resolve it from
happening again, they click on at 3c and below via a thermostat. 

bjorn_toby_wilde

BooJewels said:

grumpy_codger said:

Sometimes it can be easy to disconnect the (white plastic) condensate pipe near the boiler and to collect the condensate temporally to a bucket (that you'll have to empty regularly)

That's actually one of the solutions I was considering - I gave it a test pull to see how tight the fitting was, to see if I could bypass the external bit - but it felt tighter than I was prepared to risk - and it's high enough that I'd need to source the right size of hose to join to it etc.  But one of the future options I might have suggested was a switchable valve at that junction, so I could use a hose on it when very cold outside.

The fittings will be (are normally) solvent welded. If so then you shouldn’t be able to pull them apart. Have a look and you should be able to tell.

It freezes because essentially it just trickles out of the boiler periodically rather than gushing out all at once.

Eldi_Dos

ashe said:

Eldi_Dos said:

@ ashe

Could you instal a interception point on the pipe and use that to introduce a salt water solution into pipe, see if that works its way down and clears the ice blockage?

Potentially - i think I'll just get the trace heating thing done though as should hopefully resolve it from
happening again, they click on at 3c and below via a thermostat. 

Could go for belt and braces approach and get both done at same time, that way if trace heating fails or gets overpowered you have a easy to use back up.

QrizB

My old Worcester boiler had a syphon in the condensate system (a bit like an automatic flushing cistern on a urinal) so that condensate was released as a series of slugs rather than a continuous trickle.

It was meant to reduce the risk of the drain freezing up, and it seemed to work; we didn't get a frozen drain any time on the 19 years we had the boiler.