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Another boiler story!

Community Veteran
Posts: 2,282
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Registered: 04-08-2009

Another boiler story!

My mother-in-law is nearly 90. She recently moved into a flat which has a two year old condensing boiler. Yesterday water started dripping out from inside the casing on to the kitchen worktop, which caused a bit of a mess before she noticed it.
Called plumber, came today, told her that "these new boilers aren't designed for very cold conditions because the condenser freezes up"!
So..  he sawed off the pipe where the water was coming from (presumably a casing drain) so she could put a bowl under it.....    Crazy
13 REPLIES
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Another boiler story!

due to have my boiler replaced next year, reading this article  http://www.condensingboiler.org.uk/  that it, no condensing boiler for me,  They are very honest
Community Veteran
Posts: 2,282
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Registered: 04-08-2009

Re: Another boiler story!

He's not correct in saying that the only design of condensing boiler is one with a secondary heat exchanger where condensation takes place. His list only gives a few makes, and all of those listed are of this type.
There is also a type where the condensation takes place on the boiler coil itself and just drains away from there, hence no separate condenser to freeze up. To get this to work, you have to regulate the dewpoint of the flame exhaust (ie excess oxygen) very carefully so that condensation takes place right up to 57C, but remember that condensation will still happen if the return water temp is below 57C. The outlet temp doesn't have to be below that temp. but all the better if it is.
That's why it's better to run the heating all the time at a low flow temperature so that condensation can take place completely.
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Another boiler story!

but reading his article it wont work with standard radiators either, flowing water is too cold
Community Veteran
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Registered: 04-08-2009

Re: Another boiler story!

Now I really do know he's talking Bollocks!
You don't need special radiators. All you need to do to keep the house at the required temperature, assuming that it's reasonably well insulated, is to replace the heat that it's losing. A "normal" boiler heats the water in cycles, such as raising it to 70C and then letting it drop to 55C. If the house is extremely well insulated that cycle might be something like 50C down to 35C etcetc.. The idea of a properly installed and designed condensing system is that it runs constantly at a very low temperature, which still does the job but doesn't cycle, and therefore condenses all the time. Most of the condensing units which I have seen, and which are UK designed, can do this, but for some unknown reason the idiots that install them don't set them up to run constantly. They probably think that the house won't be warm enough so just put a standard room thermostat on them, which of course makes them cycle. Perhaps the only criterion is to ensure that the radiator pipes are at least half inch diameter, so that flow rates are high enough to each radiator.
My house has been kept toasty over the last few weeks with a boiler flow temp of no more than 50C, hence condensing.
dick:red Avoidance of swear filter edited as per forum rules.
N/A

Re: Another boiler story!

Have reported on this in the other thread and yes, these boilers seem to be packing up due to the condensate pipe freezing.  Our Worcester-Bosch was new in February of this year.  We had it re-sited on the integral garage wall so that we could access it easily (it used to be in the loft over it). 
The pipe was sited through the wall and into the drain (not particularly exposed) but it froze up twice.  It froze  a second time despite being lagged so we got some thicker lagging and put aluminum foil over it too. Last week  we had the plumber in to re-site it inside.  Only problem now is that we have to empty the receptacle but it is a small price to pay for peace of mind.  We will probably move it back when the weather improves. 
Day before yesterday we had to go and help my friend across the road because same thing had happened (same boiler too).  Hers is in the loft of the bungalow so had to use a ladder and thaw out the entire  length of the pipe.  Our men have now thoroughly lagged this and hopefully should be OK.  She has British Gas cover but could not get through.  In any case, this isn't covered so she would probably have been charged as it isn't a boiler fault.
Gas fitters are making a killing on this problem - at least some will have a happy Christmas!
Oh and regarding radiators - ours aren't special ones.
Community Veteran
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Registered: 04-08-2009

Re: Another boiler story!

Just out of interest, there is an Industry Standard Paper on the subject of condensate drains which states that they should be routed INTERNALLY wherever possible, and NEVER solidly connected to the boiler casing. If you allow the condensate to drain into a simple open tun-dish below the boiler (preferably visible), and then allow the tun-dish to drain away down a pipe, then if the drain pipe does freeze, it won't stop the flow of condensate. It might make a bit of a mess if it overflows but at least the boiler stays running. I wonder how many people who have gone away this Xmas will return to find their houses frozen solid!
Moderator
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Re: Another boiler story!

Looks like a very busy time for the plumbing industry.
Customer and Forum Moderator.
Product of the Tyrell Corporation
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Another boiler story!

orrible condensate
Quote
The difficulty of disposing of the condensate (water) has to some degree been overcome by allowing it to collect in the base of the boiler where it can be disposed of into the drainage system. Although the condensate is acidic in nature containing traces of nitric and sulphurous acids.

Tests have been conducted on materials from which domestic drains are constructed and the following conclusions reached. Drains made of plastic material and clayware showed insignificant damage while cast iron is likely to be affected in the long term and gives rise to staining. Cement and concrete products appeared to be affected more seriously
than other materials. This could lead to problems in older properties having salt-glazed drain pipes with cement joints. In practice, however, the adverse effects due to condensation are unlikely to be serious as it will be appreciated that it will be diluted very quickly by the discharges from sanitary appliances.
N/A

Re: Another boiler story!

Quote
Looks like a very busy time for the plumbing industry.

I'm thinking of cashing in on my new-found skills with unblocking condensate pipes.  Wondering if I should advertise!  Wink
N/A

Re: Another boiler story!

Quote
Looks like a very busy time for the plumbing industry.

I'm thinking of cashing in on my new-found skills with unblocking condensate pipes.  Wondering if I should advertise!   Roll eyes
Community Veteran
Posts: 2,282
Thanks: 218
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Registered: 04-08-2009

Re: Another boiler story!

If you can do that by warming up the weather you've made a fortune!  Grin
pierre_pierre
Grafter
Posts: 19,757
Registered: 30-07-2007

Re: Another boiler story!

Quote
Wondering if I should advertise!  Roll eyes

you just have - twice
Community Veteran
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Registered: 02-08-2007

Re: Another boiler story!

Not long after we got a condensing boiler it kept cutting out (Baxi) As it was under guarantee the guy from Baxi came out to sort it out.
In the boiler there is a small plastic chamber which fills up with the condensate and when this reaches a certain level it empties based on some syphon system, if this fails the water level gets a little higher and reaches an electrical sensor that automatically shuts the boiler down until the chamber is emptied.
I was amazed to see that he disconnected the wire to the sensor, left it disconnected and said it was an unnecessary safety feature, since then the boiler has worked fine for the past 7 years with no problems despite my worry about what would happen if the chamber overfilled.
Under no circumstances would I advise anyone reading this to take the same course of action (I think it might be illegal to fiddle with any gas appliance) but post it as a matter of interest.