Hi all,

I have a intergas boiler with a developing limescale problem on the domestic hot water side. Taking the heat exchanger out looks to be impractical, so I thought I'd try the alternative technique of circulating descaler through it in situ by connecting up a pump and a bucket of DS3 descaler to the nearby hot and cold washing-machine valves.

I can easily pump cold water through the heat exchanger this way, but as soon as I introduced hot water (by pouring it into the bucket) the pump gave up. To be fair it was the cheapest drill-attached pump I could find:
https://www.amazon.co.uk/Wolfcraft-2.../dp/B0001P1972

Any suggestions for a pump which is up to pumping hot acidic water?

Cheers!

Martin

On 16/02/2018 17:02, Martin Pentreath wrote:
Hi all,

I have a intergas boiler with a developing limescale problem on the domestic hot water side. Taking the heat exchanger out looks to be impractical, so I thought I'd try the alternative technique of circulating descaler through it in situ by connecting up a pump and a bucket of DS3 descaler to the nearby hot and cold washing-machine valves.

I can easily pump cold water through the heat exchanger this way, but as soon as I introduced hot water (by pouring it into the bucket) the pump gave up. To be fair it was the cheapest drill-attached pump I could find:
https://www.amazon.co.uk/Wolfcraft-2.../dp/B0001P1972

Any suggestions for a pump which is up to pumping hot acidic water?

Have you got a spare CH circulator pump?

Failing that, could you use two buckets and a bit of gravity - place one
with the DS3 higher, and let it syphon through to the lower one?

(you would have to manually empty the lower bucket back into the top
again from time to time!)

--
Cheers,

John.

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Martin Pentreath explained on 16/02/2018 :
Hi all,

I have a intergas boiler with a developing limescale problem on the domestic
hot water side. Taking the heat exchanger out looks to be impractical, so I
thought I'd try the alternative technique of circulating descaler through it
in situ by connecting up a pump and a bucket of DS3 descaler to the nearby
hot and cold washing-machine valves.

I can easily pump cold water through the heat exchanger this way, but as soon
as I introduced hot water (by pouring it into the bucket) the pump gave up.
To be fair it was the cheapest drill-attached pump I could find:
https://www.amazon.co.uk/Wolfcraft-2.../dp/B0001P1972

Any suggestions for a pump which is up to pumping hot acidic water?

Cheers!

Martin

A normal electric central heating pump should be OK for that, but they
are not self priming, so would need to be sucking from a water level
above them. Bucket above the pumps level.

Thanks John and Harry. I was just looking at cheap central heating pumps, although the siphon idea appeals to my tight fist. I might give it a go first.

On Friday, 16 February 2018 17:02:07 UTC, Martin Pentreath wrote:
Hi all,

I have a intergas boiler with a developing limescale problem on the domestic hot water side. Taking the heat exchanger out looks to be impractical, so I thought I'd try the alternative technique of circulating descaler through it in situ by connecting up a pump and a bucket of DS3 descaler to the nearby hot and cold washing-machine valves.

I can easily pump cold water through the heat exchanger this way, but as soon as I introduced hot water (by pouring it into the bucket) the pump gave up. To be fair it was the cheapest drill-attached pump I could find:
https://www.amazon.co.uk/Wolfcraft-2.../dp/B0001P1972

Any suggestions for a pump which is up to pumping hot acidic water?

Cheers!

Martin

do you need to circulate it? Fill & let sit should work


NT

Something like an eversible bilge pump?
Brian

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"Martin Pentreath" wrote in message
...
Hi all,

I have a intergas boiler with a developing limescale problem on the domestic
hot water side. Taking the heat exchanger out looks to be impractical, so I
thought I'd try the alternative technique of circulating descaler through it
in situ by connecting up a pump and a bucket of DS3 descaler to the nearby
hot and cold washing-machine valves.

I can easily pump cold water through the heat exchanger this way, but as
soon as I introduced hot water (by pouring it into the bucket) the pump gave
up. To be fair it was the cheapest drill-attached pump I could find:
https://www.amazon.co.uk/Wolfcraft-2.../dp/B0001P1972

Any suggestions for a pump which is up to pumping hot acidic water?

Cheers!

Martin

On 16/02/2018 17:34, Martin Pentreath wrote:
Thanks John and Harry. I was just looking at cheap central heating pumps, although the siphon idea appeals to my tight fist. I might give it a go first.

Certainly what I would start with, on the KISS principle.

That said, small 12 volt bilge pumps are pretty cheap, I have one
knocking around somewhere that I used for another little project. No
electrocution risk!

For the benefit of the archive I thought I should follow up with how I got on with descaling the DHW component of the heat exchanger of my intergas boiler.

In the end I bought a very cheap submersible pump from Amazon for £27, one of these
https://www.amazon.co.uk/gp/aw/d/B01...?ie=UTF8&psc=1

I put it in a bucket with about a gallon of dissolved Fernox DS3 descaler. I used one of these to connect a length of garden hose pipe to the outlet of the pump
https://www.amazon.co.uk/gp/aw/d/B00...?ie=UTF8&psc=1

I connected the other end of the hose pipe to the cold valve that feeds the washing machine. This formed the flow to pump the descaling fluid into the boiler's heat exchanger. For the return I connected another length of hose pipe to the hot washing machine valve (a remnant of an earlier era of washing machines), with its other end going into the bucket.

I turned off the mains water coming into the house, so what I ended up with was a circuit from the bucket via the pump through the plumbing for the washing machine valve, through the heat exchanger and back to the bucket again.

I ran the pump like this for about 20 minutes. I found that if the boiler was switched on then the rate of flow produced by the pump was enough to trigger the combi's flow detector and the boiler flicked on to heat the DS3 solution as it passed through the heat exchanger, which I assumed would help with the descaling reaction. I didn't want the fluid to get anything beyond tepid for the sake of the pump so I turned the boiler off again after only about 10 or 15 seconds of this.

Everything ticked along smoothly with the fluid slowly looking a little dirty. After 20 minutes I reversed the rate of flow by reversing the hoses in order to pump the fluid in the opposite direction in the hope that this would make a more thorough job of the descaling. Then for the last 20 minutes I went back to the original direction of flow.

Finally I disconnected everything, shut the washing machine valves, turned back on the water and made sure to run plenty of both hot and cold water from every tap in the house to remove any traces of the DS3.

Its not as satisfying a job as removing the heat exchanger because you can't actually see the extent to which the descaling has visibly improved matters. However removing the heat exchanger is not an option with the intergas boiler.

In retrospect I am not sure whether DS3 is strictly suitable for use with potable water. However I made sure to give the system an extremely thorough flushing out afterwards. An alternative plan would be to buy substantial quantities of vinegar, or to use citric acid, although to what extent they are compatible with aluminium I don't know.

On 07/03/2018 21:12, Martin Pentreath wrote:
For the benefit of the archive I thought I should follow up with how
I got on with descaling the DHW component of the heat exchanger of my
intergas boiler.

In the end I bought a very cheap submersible pump from Amazon for
£27, one of these
https://www.amazon.co.uk/gp/aw/d/B01...?ie=UTF8&psc=1

I put it in a bucket with about a gallon of dissolved Fernox DS3
descaler. I used one of these to connect a length of garden hose pipe
to the outlet of the pump
https://www.amazon.co.uk/gp/aw/d/B00...?ie=UTF8&psc=1

I connected the other end of the hose pipe to the cold valve that
feeds the washing machine. This formed the flow to pump the descaling
fluid into the boiler's heat exchanger. For the return I connected
another length of hose pipe to the hot washing machine valve (a
remnant of an earlier era of washing machines), with its other end
going into the bucket.

I turned off the mains water coming into the house, so what I ended
up with was a circuit from the bucket via the pump through the
plumbing for the washing machine valve, through the heat exchanger
and back to the bucket again.

I ran the pump like this for about 20 minutes. I found that if the
boiler was switched on then the rate of flow produced by the pump was
enough to trigger the combi's flow detector and the boiler flicked on
to heat the DS3 solution as it passed through the heat exchanger,
which I assumed would help with the descaling reaction. I didn't want
the fluid to get anything beyond tepid for the sake of the pump so I
turned the boiler off again after only about 10 or 15 seconds of
this.

Everything ticked along smoothly with the fluid slowly looking a
little dirty. After 20 minutes I reversed the rate of flow by
reversing the hoses in order to pump the fluid in the opposite
direction in the hope that this would make a more thorough job of the
descaling. Then for the last 20 minutes I went back to the original
direction of flow.

Finally I disconnected everything, shut the washing machine valves,
turned back on the water and made sure to run plenty of both hot and
cold water from every tap in the house to remove any traces of the
DS3.

Its not as satisfying a job as removing the heat exchanger because
you can't actually see the extent to which the descaling has visibly
improved matters. However removing the heat exchanger is not an
option with the intergas boiler.

Did it fix the original problem though?

In retrospect I am not sure whether DS3 is strictly suitable for use
with potable water. However I made sure to give the system an
extremely thorough flushing out afterwards. An alternative plan would
be to buy substantial quantities of vinegar, or to use citric acid,
although to what extent they are compatible with aluminium I don't
know.

If flushed out it should be fine.




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Here's an American video showing essentially the approach which I took, except he uses a much more expensive submersible pump and also uses vinegar instead of DS 3 as the descaling chemical.

https://youtu.be/8lw0iL7yBcA

Also Americans seem to have lovely service valves just below their boilers. These allow easy draining of the DHW heat exchanger and also easy pumping through of the descaling chemicals. See the video at 1:12. Can anyone point me in the direction of a similar type of valve to put on the domestic hot water pipes to my boiler? I reckon it would be worth a little bit of replumbing in order not to have to use the valves for the washing machine which are not exactly conveniently located.