MODERN CONDENSING BOILERS HAVE A SERIOUS DESIGN FLAW

Time_Tech

Here's the problem: Modern Condesing boilers work perfectly in the summer when the weather is warm, and you don't need any heat, and then fail when its cold and you do need heat....Due to an apparently common and obvious design flaw.

I recently bought a brand new boiler made by a very popular manufacturer, and installed by an equally popular installation company. It is installed in the airing cupboard upstairs, in the same location as the old boiler was.

Yesterday the new boiler failed, leaving us with no hot water or heating, and temperatures in the house fell to just 13c (it was -8c outside).

The reason for the boiler failure was its outside 'drain' (or condensing) pipe freezing up. This is apparently very common on all condensing boilers. Even though this pipe is fully lagged, it still froze up causing the boiler fail.

The solution, according to the boiler industry, is point you to a video telling you NOT to call a boiler engineer. Instead they tell you to go outside in the freezing cold, and pour warm water over the boilers 'drain' pipe.
This may be OK if it is located at ground level - and you don't slip on the ice whilst doing it.
But its properly dangerous if it is located on a second floor or above, and it involves climbing a 10 ft ladder, in icy conditions, to get to the pipe.

No solution to this obvious problem has been provided 'as standard' by the installer, or the manufacturer. Do boiler manufacturers expect customers to go out in the freezing cold with buckets of water to heat up the drain pipe every time this happens?  What if the resident is elderly and cannot get out of the house - and is being being told NOT to call an engineer?

I've written to the manufcturer and look forward to hearing what they suggest to resolve this design flaw.

MattMattMattUK

Time_Tech said:

Here's the problem: Modern Condesing boilers work perfectly in the summer when the weather is warm, and you don't need any heat, and then fail when its cold and you do need heat....Due to an apparently common and obvious design flaw.

I recently bought a brand new boiler made by a very popular manufacturer, and installed by an equally popular installation company. It is installed in the airing cupboard upstairs, in the same location as the old boiler was.

Yesterday the new boiler failed, leaving us with no hot water or heating, and temperatures in the house fell to just 13c (it was -8c outside).

The reason for the boiler failure was its outside 'drain' (or condensing) pipe freezing up. This is apparently very common on all condensing boilers. Even though this pipe is fully lagged, it still froze up causing the boiler fail.

The solution, according to the boiler industry, is point you to a video telling you NOT to call a boiler engineer. Instead they tell you to go outside in the freezing cold, and pour warm water over the boilers 'drain' pipe.
This may be OK if it is located at ground level - and you don't slip on the ice whilst doing it.
But its properly dangerous if it is located on a second floor or above, and it involves climbing a 10 ft ladder, in icy conditions, to get to the pipe.

No solution to this obvious problem has been provided 'as standard' by the installer, or the manufacturer. Do boiler manufacturers expect customers to go out in the freezing cold with buckets of water to heat up the drain pipe every time this happens?

They expect installers to install in a way that reduces the probability of the pipe freezing. Most modern installations will put the pipe into the properties waste water, those that go external should use a minimum of a 30mm internal diameter pipe and it should be lagged/insulated. Many installers will not even bother with the internal drain and will use a 15mm pipe externally with minimal lagging, hence the problem. The issue is not the boiler, it is poor installation.

Time_Tech said:

What if the resident is elderly and cannot get out of the house - and is being being told NOT to call an engineer?

People are told not to call an engineer where fixing it themselves is possible. If they are unable to fix it themselves then a friend or family member would make more sense, rather than an engineer with a £150+ callout fee.

Time_Tech said:

I've written to the manufcturer and look forward to hearing what they suggest to resolve this design flaw.

Proper installation. 

Time_Tech

Thanks for the comment and feedback on this. Its interesting to note that a popular online retailer sells an electrical heating cable that can heat up the condensing (drain) pipe when temperatures fall below freezing. It does not cost much and a friend, who is an electrician, installed one himself in his own house to stop the problem. Question is - why do boiler manufacturers not offer this as standard? As it seems like a sensible solution.

MattMattMattUK

Time_Tech said:

Thanks for the comment and feedback on this. Its interesting to note that a popular online retailer sells an electrical heating cable that can heat up the condensing (drain) pipe when temperatures fall below freezing. It does not cost much and a friend, who is an electrician, installed one himself in his own house to stop the problem. Question is - why do boiler manufacturers not offer this as standard? As it seems like a sensible solution.

They do not offer it because if the boiler is installed properly it is not required. Using the electrical heater is a bodge to mitigate an installation which is not in line with the manufacturer's instructions. 

[Deleted User]

I I think that I am correct in saying that early condensing boilers had a constant drip flow of condensate. Most boilers these days have an in boiler condensate water store and syphon. The water is not in most pipes long enough to freeze.

That said, I have never understood the logic of putting boilers and PV inverters in loft spaces. Apart from the problems of access, circuit boards subject to low and high temperatures are prone to early failure.

pseudodox

The term "Popular Installation Company" does not mean competent professional installation.  I have just ordered a new boiler to be fitted in the spring.  It is a Worcester Bosch and will be installed by my local accredited installers, which will give me the peace of mind of a 12 year warranty. If something like the OPs experience happens to me then I will not be watching videos, but expecting the installers to come out pronto and sort it out.

My current condensate pipe does run out through to the exterior of my house but has never frozen.  However the new boiler will have the pipe run through kitchen units and into the drain from the sink.  They will cut holes through the back of my cupboards to do this and that is what I regard as a professional advice and competent installation.  It may be a bit more work all round but apparently it is what is specified these days by the boiler manufacturer and sounds eminently sensible to me.

Lorian

Plumbing it to an internal drain if available removes the risk. If it has to go outside it needs to be in plastic, insulated and have a good fall. Not a boiler design fault.

daveyjp

Its not a boiler design flaw its a lazy gas installer flaw.  When jnstalled correctly a condensate should never freeze.  Either install internally, or if external plumb into a larger diameter waste pipe at a steep angle and lag it or install  a heat trace cable.

A friend went to a property last week to quote for a new bathroom.  Last year the owners had the boiler moved to the loft.  However because it was a pain getting the condensate to a drain the flawed engineer simply drilled hole in the wall and stuck 100mm of pipe outside and left it to drip.  Imagine trying to defrost that.

Some flawed engineers plumb the pipe into a non open ended pipe such as a drainage downpipe which can get block underground.  If there is a blockage the water backs up and floods the boiler.

greyteam1959

This was a huge issue do a few years ago go during the last big freeze in the UK a few years ago.

magickmagpie

My 5 year old oil condensing boiler has a condensate pipe that runs to an external drain (although most of the pipework is in the unheated scullery along with the boiler.) About 18" of pipe (which was lagged by the installers) runs down an outside wall and into a drain. I've never had a problem with the pipe freezing in normal winter conditions. On the rare occasions the temperature overnight falls to under -10 degrees (just before Xmas this year!!) I've inspected the outlet pipe in the morning and found a small amount of ice in the bottom of it, but not enough to block the pipe, and this was easily melted by using some warm water. I imagine that if I didn't melt this ice when I see it, and outside temperatures remained below freezing for several days, the pipe would eventually block - but this has never happened in the five years I've had the boiler.

molerat

My daughter did have uninsulated 15mm plastic with an almost horizontal run with a sag in it - so an uphill section - and never had it freeze.  Her new boiler has 32mm and well insulated with good drops.