Well, after thinking the combi boiler was fixed, it has started playing
up again.
Alpha 240P, around 10 years old.
DHW runs for 2 minutes, then cuts out for 20 seconds or so, then
restarts, cuts out after a 2 minutes or so etc etc.

New DHW heat exchanger fitted, as this was pointed as the most likely
cause of the fault. It did run well for 2 weeks after.
Rang Alpha, who seemed to think it could now only be the Primary temp
sensor failing, or the primary heat exchanger fouled up.

New sensor fitted this week. No change at all, so it looks like it is
the primary heat exchanger.

The sytem had Screwfix own brand cleaner in it for a week, then flushed
out.
Is it worthwhile putting a good quality cleaner in it (Fernox FS3?),
then flushing through again?
The best way to flush through - remove both CH pipes from the bottom of
the boiler, then attach hosepipes to them, and flush through like that?

Any other thing I should look at?

And if flushing through isnt the thing to cure it, is it going to be
worthwhile buying a new heat exchanger, taking out the old one to clean
it, or just getting a new boiler?

Thanks
Alan.
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In article ,
(A.Lee) writes:
Well, after thinking the combi boiler was fixed, it has started playing
up again.
Alpha 240P, around 10 years old.
DHW runs for 2 minutes, then cuts out for 20 seconds or so, then
restarts, cuts out after a 2 minutes or so etc etc.

New DHW heat exchanger fitted, as this was pointed as the most likely
cause of the fault. It did run well for 2 weeks after.
Rang Alpha, who seemed to think it could now only be the Primary temp
sensor failing, or the primary heat exchanger fouled up.

New sensor fitted this week. No change at all, so it looks like it is
the primary heat exchanger.

The sytem had Screwfix own brand cleaner in it for a week, then flushed
out.
Is it worthwhile putting a good quality cleaner in it (Fernox FS3?),
then flushing through again?
The best way to flush through - remove both CH pipes from the bottom of
the boiler, then attach hosepipes to them, and flush through like that?

Any other thing I should look at?

I would check to see if the new DHW heat exchanger has got
clogged with rust again. The timing would be about right if
there's still lots of rust in the system.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:

In article ,
(A.Lee) writes:
Well, after thinking the combi boiler was fixed, it has started playing
up again.
Alpha 240P, around 10 years old.
DHW runs for 2 minutes, then cuts out for 20 seconds or so, then
restarts, cuts out after a 2 minutes or so etc etc.


I would check to see if the new DHW heat exchanger has got
clogged with rust again. The timing would be about right if
there's still lots of rust in the system.

Well I took it all apart again. The DHW exchanger had around 4 or 5 rust
flakes in it, no more, so attention turned to the primary heat
exchanger.
I tried to undo its connecting pipes, but they were too tight to be
undone, so plan B was to flush it through again.Radiator input tap was
turned off at the boiler, leaving the output tap open, then undid the
drain point at the furthest radiator, then turn on the filling loop pipe
fully, pressure up to 1.5 bar on the meter, and coming out rather fast
from the drain.
This ran for half an hour.
Put it all back together then, and had great difficulty in getting the
pilot to stay alight.
Thermocouple seemed to be ok, so it looked like the overheat themostat
cutting off the gas, took it out, tested it for conductivity, and not a
problem. Put it back with good connections, and it did stay alight
eventually. Looks like the thermostat had a bad connection.

Tested, and found everything working as it should do.
Great.

Now, I've got some Fernox cleaning fluid here. Would it be wise to get
the whole system cleaned again this weekend?

Ta
Alan.

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"A.Lee" wrote in message
...
Andrew Gabriel wrote:

In article ,
(A.Lee) writes:
Well, after thinking the combi boiler was fixed, it has started playing
up again.
Alpha 240P, around 10 years old.
DHW runs for 2 minutes, then cuts out for 20 seconds or so, then
restarts, cuts out after a 2 minutes or so etc etc.


I would check to see if the new DHW heat exchanger has got
clogged with rust again. The timing would be about right if
there's still lots of rust in the system.

Well I took it all apart again. The DHW exchanger had around 4 or 5 rust
flakes in it, no more, so attention turned to the primary heat
exchanger.
I tried to undo its connecting pipes, but they were too tight to be
undone, so plan B was to flush it through again.Radiator input tap was
turned off at the boiler, leaving the output tap open, then undid the
drain point at the furthest radiator, then turn on the filling loop pipe
fully, pressure up to 1.5 bar on the meter, and coming out rather fast
from the drain.

Was the flow running through the heat exchanger?

This ran for half an hour.
Put it all back together then, and had great difficulty in getting the
pilot to stay alight.
Thermocouple seemed to be ok, so it looked like the overheat themostat
cutting off the gas, took it out, tested it for conductivity, and not a
problem. Put it back with good connections, and it did stay alight
eventually. Looks like the thermostat had a bad connection.

Tested, and found everything working as it should do.
Great.

Now, I've got some Fernox cleaning fluid here. Would it be wise to get
the whole system cleaned again this weekend?

Yes.

On the CH return to the boiler fit this filter:

http://www.mytub.co.uk/product_infor...product=313159
Cheap enough to buy.

http://www.pneumatex.com/default.cfm...medef=1&spr=en

It grabs all the crud and magentite and protects the boilers heat exchangers
and the rest of the system too.

You probably replaced a DHW heat exchanger for no reason. This will prevent
alot of problems.

Doctor Drivel wrote:

On the CH return to the boiler fit this filter:

http://www.mytub.co.uk/product_infor...product=313159
Cheap enough to buy.

For £108, I think i'll stick with the 'thorough flush every ten years'
method. For a new boiler it may act as peace of mind, but on an old one
it is a poor cost/benefit ratio IMO.

Ta
Alan.


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"A.Lee" wrote in message
.. .
Doctor Drivel wrote:

On the CH return to the boiler fit this filter:

http://www.mytub.co.uk/product_infor...product=313159
Cheap enough to buy.

For £108, I think i'll stick with the 'thorough flush every ten years'
method. For a new boiler it may act as peace of mind, but on an old one
it is a poor cost/benefit ratio IMO.

Then it is you that suffers the breakdowns and corrosion.

In article ,
A.Lee wrote:
Doctor Drivel wrote:

On the CH return to the boiler fit this filter:

http://www.mytub.co.uk/product_infor...product=313159
Cheap enough to buy.

For £108, I think i'll stick with the 'thorough flush every ten years'
method. For a new boiler it may act as peace of mind, but on an old one
it is a poor cost/benefit ratio IMO.

Using inhibitor on a leak free system is the cheapest way to prevent
corrosion. Filters are simply unnecessary. If they were a requirement
boiler makers would fit them.

--
*Don't byte off more than you can view *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
A.Lee wrote:
Doctor Drivel wrote:

On the CH return to the boiler fit this filter:

http://www.mytub.co.uk/product_infor...product=313159
Cheap enough to buy.

For £108, I think i'll stick with the 'thorough flush every ten years'
method. For a new boiler it may act as peace of mind, but on an old one
it is a poor cost/benefit ratio IMO.

Using inhibitor on a leak free system is the cheapest way to prevent
corrosion. Filters are simply unnecessary. If they were a requirement
boiler makers would fit them.

Alpha fit one in the boiler. You are a plantpot knowing nothing of heating
systems, so please eff off.

"Dave Plowman (News)" wrote in message
...


Using inhibitor on a leak free system is the cheapest way to prevent
corrosion. Filters are simply unnecessary. If they were a requirement
boiler makers would fit them.

Eaga insist on having a spiravent fitted to the systems they pay for.

I googled for info but its very limited.
The plumber said there was a drain on it to remove the dirt but to ignore it
as it would never get dirty as long as the inhibitor wasn't drained.
I wanted to find out how much they were as they are supposed to be extremely
good at removing air.

"dennis@home" wrote in message
...


"Dave Plowman (News)" wrote in message
...


Using inhibitor on a leak free system is the cheapest way to prevent
corrosion. Filters are simply unnecessary. If they were a requirement
boiler makers would fit them.

Eaga insist on having a spiravent fitted to the systems they pay for.

I googled for info but its very limited.
The plumber said there was a drain on it to remove the dirt but to ignore
it as it would never get dirty as long as the inhibitor wasn't drained.

until the inhibitor loses is effect then corrosion starts.

In article ,
Doctor Drivel wrote:
I googled for info but its very limited. The plumber said there was a
drain on it to remove the dirt but to ignore it as it would never get
dirty as long as the inhibitor wasn't drained.

until the inhibitor loses is effect then corrosion starts.

You change it before this happens. Still much cheaper than a filter. And
the correct way to go about things. Prevention is always better than
'cure'.

--
*Beauty is in the eye of the beer holder *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Doctor Drivel wrote:
I googled for info but its very limited. The plumber said there was a
drain on it to remove the dirt but to ignore it as it would never get
dirty as long as the inhibitor wasn't drained.

until the inhibitor loses is effect then corrosion starts.

You

Please eff off as you are a total plantpot.