edspurrier
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| posted on 18/11/07 at 04:04 PM |
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Smelly Hot Water - Any Plumbers Here?
My 2 year old house has a distinct rotten egg smell in the hot water. It's a pressurised system. The cylinder and boileer seem to work OK
otherwise, though the inlet and heating pressure guages on the cylinder always read 0.
Any thoughts before I give all my money to a local plumber?
Thanks
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craig1410
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| posted on 18/11/07 at 04:41 PM |
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Hi,
I'm no expert but going by the following website it is likely to be your magnesium anose which needs replaced.
http://www.uldrinkwell.com/drinkwell/rotten_egg_smell.html
HTH,
Craig.
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Markp
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| posted on 18/11/07 at 05:32 PM |
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last time I knew some one with smell water they had a dead pigeon in the water tank
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JoelP
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| posted on 18/11/07 at 06:04 PM |
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quote:
Originally posted by Markp
last time I knew some one with smell water they had a dead pigeon in the water tank
i heard about someone with a rotten cow in the stream that fed their (rural) house
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MkIndy7
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| posted on 18/11/07 at 06:18 PM |
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Is it an old fashioned tank fed airing cupboard type cylinder or a newer mains fed type cylinder?
Only the newer type mains fed cylinder type is likely to have a sacrifitial annode in.
Presuming by saying its a pressurised system you mean the boiler is on a filling loop, have you had to top it up much lately?
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craig1410
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| posted on 18/11/07 at 07:44 PM |
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quote:
Originally posted by MkIndy7
Is it an old fashioned tank fed airing cupboard type cylinder or a newer mains fed type cylinder?
Only the newer type mains fed cylinder type is likely to have a sacrifitial annode in.
Presuming by saying its a pressurised system you mean the boiler is on a filling loop, have you had to top it up much lately?
I was assuming he meant an unvented system because he wouldn't be drinking water out of his boiler...
For those who don't know, an unvented system has mains water fed into it via a one way valve. The hot and cold water pressure are kept at the
same level and therefore the hot water tank runs pressurised. This allows you to have a power shower without the pump which is great. I have a Santon
system which I believe has a sacrificial anode but some of the more advanced systems such as Megaflo use a very high quality stainless steel to avoid
the need for an anode.
If you have an unvented system then you won't have a cold water tank so no dead pigeons...
Cheers,
Craig.
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edspurrier
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| posted on 18/11/07 at 07:46 PM |
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Thanks all. It's a mains fed unvented system. I've just tried running it hot+++ for a bit and flushing it through thoroughly -
we'll see how it goes
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craig1410
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| posted on 18/11/07 at 07:52 PM |
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Hi Ed,
If you are in any doubts it's well worth getting it checked. Our next door neighbour's unvented tank developed a leak earlier this year
and flooded the house with hot water. Made a hell of a mess! Took nearly 6 months to dry the house out again and get it redecorated.
I don't know where you live but in Scotland there is a good website with details of SNIPEF registered plumbers including those who are certified
on unvented systems. The website is here:
http://www.needaplumber.org/
Good luck - hopefully the hot flush will sort out your problem.
Cheers,
Craig.
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MkIndy7
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| posted on 18/11/07 at 08:07 PM |
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quote:
Originally posted by craig1410
quote:
Originally posted by MkIndy7
Is it an old fashioned tank fed airing cupboard type cylinder or a newer mains fed type cylinder?
Only the newer type mains fed cylinder type is likely to have a sacrifitial annode in.
Presuming by saying its a pressurised system you mean the boiler is on a filling loop, have you had to top it up much lately?
I was assuming he meant an unvented system because he wouldn't be drinking water out of his boiler...
For those who don't know, an unvented system has mains water fed into it via a one way valve. The hot and cold water pressure are kept at the
same level and therefore the hot water tank runs pressurised. This allows you to have a power shower without the pump which is great. I have a Santon
system which I believe has a sacrificial anode but some of the more advanced systems such as Megaflo use a very high quality stainless steel to avoid
the need for an anode.
If you have an unvented system then you won't have a cold water tank so no dead pigeons...
Cheers,
Craig.
I was meaning as opposed to a tank fed heating boiler where the boiler is fed from header tank in the loft, and when the boiler water expands it can
push through an old fashioned water cylinder annular if its split and into the hot water cylinder. With it being tank fed you'd never know they
boiler side was leaking.
To be hoped I know the difference i'm the Regional HVCA apprentice of the year 
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craig1410
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| posted on 18/11/07 at 10:47 PM |
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quote:
Originally posted by MkIndy7
I was meaning as opposed to a tank fed heating boiler where the boiler is fed from header tank in the loft, and when the boiler water expands it can
push through an old fashioned water cylinder annular if its split and into the hot water cylinder. With it being tank fed you'd never know they
boiler side was leaking.
To be hoped I know the difference i'm the Regional HVCA apprentice of the year
Didn't mean to patronise...
I see where you are coming from now - I didn't realise you were talking about a leak from the tank's internal heating coils to the hot
water tank itself. Of course on an unvented system you would be more likely to find the boiler circuit increasing in pressure rather than losing
pressure because I think(?) the contents of the tank run at a higher pressure than the boiler circuit. On my system the boiler circuit runs at about
1.5 bar and I think the mains pressure is about 3 bar or maybe a bit more.
HVCA Apprentice of the year? Is that a bit like Obi Wan Kenobi? Sorry - I'm in a bit of a silly mood this evening...
Cheers,
Craig.
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MkIndy7
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| posted on 18/11/07 at 11:31 PM |
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If there both the cylinder and boiler are tank fed (from the loft)then the header tanks are at the same level and thus pressure. When the boiler
water expands it becomes higher pressure than that in the hot water cylinder... should there be any fault in the heating coil/annular then it would
push into the domestic hot water side of the cylinder. You wouldn't ever notice as both header tanks keep re-filling themselfes.
This can also happen if the boiler is on a pressurised system and the hot water cylinder is still tank fed, but in this setup you'd notice the
boiler pressure keeps dropping and you have to keep topping it up.
But if its an unvented hot water cylinder then you are correct and the approx 3bar pressure would be higher in the cylinder and pass back into the
boiler should there be a problem and make the boiler go over pressure.
Hence wanting the clarification as to which parts are unvented and which aren't.
P.s Believe me i've had a very good Master 
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craig1410
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| posted on 18/11/07 at 11:46 PM |
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I think we're on the same page - may the force be with you!
Craig.
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edspurrier
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| posted on 19/11/07 at 08:03 AM |
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Ah, excellent stuff. It's not fed fro a header tank, but there are 2 expansion vessels - one on top of the cylinder and one next to it.
There is some evidence of a leak from the vessel on top.
Thanks
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craig1410
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| posted on 19/11/07 at 08:40 AM |
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Ed,
The expansion vessel is required to take up the expansion caused by heating the water since there is a non-return valve on the cold water inlet to the
tank to prevent water from being discharged back into the mains (illegal AFAIK). There is usually a diaphragm separating the air in the expansion
vessel from the water but these can burst, although not usually after just two years...
The air pressure in the expansion vessel should balance the pressure of the water in the tank when cold and this can often increased using a pump.
Then when the water heats the diaphragm rises and provides some expansion space.
Different systems have different maintenance procedures so you should try to get the correct procedures from the manufacturer if possible or hire a
qualified plumber.
If you are doing anything with the system then make sure you are safe. Never work on it when it is full of hot water and/or pressurised. You should
switch off the boiler and allow the hot water to run down. Then turn of the cold water inlet and depressurise via a hot water tap.
Good luck,
Craig.
ps. The pressure vessels are quite cheap to buy if you think yours is leaking. Just use google to find a new one.
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