UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Posted to uk.d-i-y
Neil
 
Posts: n/a
Default Limescale

I have been told I need to replace the secondary heat exchanger on my
Potterton Combi 80 due to limescale stopping the HW from remaining hot
(CH is fine)

As the boiler is approx 5-6 years old, would money be better spent on a
new condensing boiler?

Is there no way of removing the limescale rather than purchasing a
brand new exchanger?

neil

  #2   Report Post  
Posted to uk.d-i-y
Andrew Gabriel
 
Posts: n/a
Default Limescale

In article .com,
"Neil" writes:
I have been told I need to replace the secondary heat exchanger on my
Potterton Combi 80 due to limescale stopping the HW from remaining hot
(CH is fine)

As the boiler is approx 5-6 years old, would money be better spent on a
new condensing boiler?

Is there no way of removing the limescale rather than purchasing a
brand new exchanger?


I cleaned up a friend's one a few months back. It was quite easy.
That was a Baxi 80, IIRC. The instructions will tell you how to
remove and replace the heat exchanger. Watch that when you release
the pressure, the water doesn't spew out over anything important
such as the circuit boards, gas valve, etc.
Buy a tub of Furnox DS-3, dissolve some in warm water, and keep
pouring through the heat exchanger until it stops fizzing. You
will likely need to mix up fresh solution several times (each
time it goes blue, IIRC). Try to avoid getting any undissolved
crystals of DS-3 into the exchanger, and flush it out well
afterwards.

Flush out the other side too with a strong water jet -- it can
fill with black crud which floats around in older heating systems
(particularly if you didn't have enough inhibitor at some time).

--
Andrew Gabriel
  #3   Report Post  
Posted to uk.d-i-y
Neil
 
Posts: n/a
Default Limescale

Thanks Andrew.

When you say it was quite easy to clean, do you mean for a Corgi
registered person?

I had a quote of £520 to have it replaced (£200 for the parts, the
rest labour). The engineer mentioned that another alternative would be
to connect a special pump to the cold and hot inlets that pumps Furnox
through the whole system.

Can anyone recommend any of these pumps or whether they work?

Can I get the same effect from any of the other limscale removers I
have seen on the Internet that use magents/radio/etc?

Regards
Neil

Andrew Gabriel wrote:
In article .com,
"Neil" writes:
I have been told I need to replace the secondary heat exchanger on my
Potterton Combi 80 due to limescale stopping the HW from remaining hot
(CH is fine)

As the boiler is approx 5-6 years old, would money be better spent on a
new condensing boiler?

Is there no way of removing the limescale rather than purchasing a
brand new exchanger?


I cleaned up a friend's one a few months back. It was quite easy.
That was a Baxi 80, IIRC. The instructions will tell you how to
remove and replace the heat exchanger. Watch that when you release
the pressure, the water doesn't spew out over anything important
such as the circuit boards, gas valve, etc.
Buy a tub of Furnox DS-3, dissolve some in warm water, and keep
pouring through the heat exchanger until it stops fizzing. You
will likely need to mix up fresh solution several times (each
time it goes blue, IIRC). Try to avoid getting any undissolved
crystals of DS-3 into the exchanger, and flush it out well
afterwards.

Flush out the other side too with a strong water jet -- it can
fill with black crud which floats around in older heating systems
(particularly if you didn't have enough inhibitor at some time).

--
Andrew Gabriel


  #4   Report Post  
Posted to uk.d-i-y
Andrew Gabriel
 
Posts: n/a
Default Limescale

In article .com,
"Neil" writes:
Thanks Andrew.
When you say it was quite easy to clean, do you mean for a Corgi
registered person?


No, I mean for me. I have installed heating systems, but I'm
not CORGI, and I didn't install this one. The difficult part
will be getting it out of the boiler. If you aren't familiar
with such plumbing, then you might not want to tackle something
like that as a first job. Cleaning it once it's out is easy.

I had a quote of £520 to have it replaced (£200 for the parts, the
rest labour). The engineer mentioned that another alternative would be
to connect a special pump to the cold and hot inlets that pumps Furnox
through the whole system.
Can anyone recommend any of these pumps or whether they work?


Sounds like a power flush, except in your case, the blockage is
probably on the hot water side rather than the closed loop side,
so it won't work. If you are DIY'ing it and your time is therefore
not accounted for, then it's better to spend the effort cleaning
the plate exchanger. For a CORGI, maybe they don't bother and just
fit a new one, since if they spend the time cleaning it and then
find it's knackered, there's both paying for the time to clean it
and cost of a new one.

Can I get the same effect from any of the other limscale removers I
have seen on the Internet that use magents/radio/etc?


Certainly not once it's blocked, even if you do believe in the
magical abilities of a couple of flashing LED's to soften the
water.

--
Andrew Gabriel
  #5   Report Post  
Posted to uk.d-i-y
Neil
 
Posts: n/a
Default Limescale

Thanks again.

Apparently the reason for replacing a part rather than cleaning it was
down to the legality of having to dispose of the chemicals afterwards
in the right way.

I just looked at the pipes the chap said to cut and place the pump on -
the mains water inlet and the HW outlet. Would that still have no
effect as you mention above?

To be honest I'm desperate to perform what you did and remove the part
but I admit my plumbing is basic. Is it a case of 'unscrew this, remove
part, unclip that' etc. or were there situations where specialist
knowledge/tools or experience is needed? The engineer mentioned the
tricky bit is normally putting the heat exchanger back in.

Neil



  #6   Report Post  
Posted to uk.d-i-y
Andrew Gabriel
 
Posts: n/a
Default Limescale

In article .com,
"Neil" writes:
Thanks again.

Apparently the reason for replacing a part rather than cleaning it was
down to the legality of having to dispose of the chemicals afterwards
in the right way.


The plumber was telling you a lie. The chemical is eactly the
same as you use to descale your kettle, and you do the same with
it when you've finished.

I just looked at the pipes the chap said to cut and place the pump on -
the mains water inlet and the HW outlet. Would that still have no
effect as you mention above?


Oh, that might work, but I never heard of anyone cleaning a plate
exchanger that way. Anyway, you should really clean both sides.
The other side won't be scaled up, but it might well have debris
from the heating system in it which can be washed out.
Oh, and what was he suggesting you should do with the cleaning
chemicals afterwards? ;-)

I suspect your plumber doesn't know what he's doing or is just
plain dishonest, but it would be interesting to see if any of the
plumbers/heating engineers in this newsgroup think this is a
standard way to clean a plate exchanger.

To be honest I'm desperate to perform what you did and remove the part
but I admit my plumbing is basic. Is it a case of 'unscrew this, remove
part, unclip that' etc. or were there situations where specialist
knowledge/tools or experience is needed? The engineer mentioned the
tricky bit is normally putting the heat exchanger back in.


Look at the boiler servicing instructions. It will tell you how to
remove and replace the plate exchanger (secondary heat exchanger).
IIRC, it is held in by just 2 or 4 screws, and there are no additional
plumbing connections (if I'm thinking of the right boiler). The tricky
part is that it's behind the gas valve which makes access harder (I
was also replacing the gas valve, so I had the valve out at that point
and just protected the exposed gas pipes from getting water in them).
Also, make sure you release the heating system pressure, or ~5 litres
of water will spray out from the pressure vessel all over the
electrics when you unscrew the plate exchanger -- it should say this
in the servicing manual.

However, I don't want to push you into doing something you are
uncomfortable tackling, and I would suggest you find another
heating engineer.

--
Andrew Gabriel
Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Does regular descaling damage a kettle and make it more susceptible to limescale? Peter UK diy 12 August 3rd 05 10:18 PM
Removing limescale Chris Styles UK diy 25 July 27th 05 09:55 PM
Washing Machine Limescale Trouble Paul S UK diy 5 December 9th 04 12:10 AM
Removing limescale from chrome taps Oldskoolskater UK diy 13 October 9th 03 04:52 PM
Washing machine - waste pipe limescale IMM UK diy 2 July 15th 03 11:25 PM


All times are GMT +1. The time now is 02:57 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"