A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew

"Mathew Newton" wrote in message
...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.

Doctor Drivel wrote:

"Mathew Newton" wrote in message
...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.


A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
put the acid back (or a fresh lot)
I think the danger is that the crud may be masking leaks, which might
start to flow freely once the corrosion has gone.
I remember descaling a rad on an old Morris Minor once (anti freeze
wasn't standard back then). It functioned perfectly for a few days, and
then the bottom fell out

"Stuart Noble" wrote in message
...
Doctor Drivel wrote:

"Mathew Newton" wrote in message
...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.

A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
put the acid back (or a fresh lot)
I think the danger is that the crud may be masking leaks, which might
start to flow freely once the corrosion has gone.
I remember descaling a rad on an old Morris Minor once (anti freeze wasn't
standard back then). It functioned perfectly for a few days, and then the
bottom fell out

Plate heat exchangers are stainless steel.

On 7 May, 14:55, Stuart Noble wrote:
Doctor Drivel wrote:

Fernox DS3 to descale. *DS = Descale.

A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
*put the acid back (or a fresh lot)

Thank you both for the suggestions. One thing I didn't specify was
that it is actually the primary (CH) side of the heat exchanger that
is suspected as being blocked... do you think this would be down to
limescale? Or crap from the CH system? It's had inhibitor for the past
7 years, but before that I really don't know. I fitted an inline
strainer a couple of years ago - it'll be interesting to see if that's
got anything in it.

Mathew

"Mathew Newton" wrote in message
...
On 7 May, 14:55, Stuart Noble wrote:
Doctor Drivel wrote:

Fernox DS3 to descale. DS = Descale.

A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
put the acid back (or a fresh lot)

Thank you both for the suggestions. One thing I didn't specify was
that it is actually the primary (CH) side of the heat exchanger that
is suspected as being blocked... do you think this would be down to
limescale? Or crap from the CH system? It's had inhibitor for the past
7 years, but before that I really don't know. I fitted an inline
strainer a couple of years ago - it'll be interesting to see if that's
got anything in it.

Mathew


Firstly, put a Magnaclean filter on the return to the boiler. Use cleanser
to remove the crud. Use DSL to clean the plate heat exchnmager. After
cleaning use a hose to clean it out. Re-fill with OX-100 in the system
after a few flushes.

After one month check the Magnclean filter and clean if necessary. After 2
months check again. If still crud then keep cleaning filter ever 2 months
until clean. Then clean every year.

On 7 May, 14:34, "Doctor Drivel" wrote:
"Mathew Newton" wrote in message

...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.

I have to do this job periodically on my Ariston Microgenus. Speaking
as a tight-fisted southerner it's definitely worth it, and I remember
the joy throughout the household the first time I did it and restored
full flow and heat to the shower! Ah the rewards of DIY.

Anyway, I agree with Drivel that DS3 is the stuff for descaling.
However, sometimes in my case the clogging is on the primary side due
to iron oxide (rather than limescale on the secondary side). In this
case I don't know of any chemicals which will shift it, and it's just
a matter of flushing it through at as high a pressure as you can
manage, coupled with some knocking about to dislodge stuff. By the
way, I find a cheap drill-attachment pump with a couple of suitable
bits of hose is good for circulating hot DS3 solution through the heat
exchanger.

If it is black iron oxide causing the problem then you don't have
enough inhibitor in the system, and the whole system will need a flush
through and fresh inhibitor.

I've managed to keep mine going for the last five years like this.
It's a couple of hours work, most of which is just leaving it soaking.

Cheers!

Martin

On Wed, 07 May 2008 06:21:45 -0700, Mathew Newton wrote:

A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB 24CDi
combi.

Given the potential uncertainty surrounding the fault/cure, and the fact
that I am a tight Northerner, I was wondering about ways to avoid/ delay
the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I was
wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11 years
old by the way).

Mathew

The down side of descaling the the only DHW heat exchanger you have is:
1) the down time on the boiler whilst you are doing the job.
2) if it springs a leak either internally or externally your shafted.
3) a new one will have new washers and O-rings to make a good refit.

As a pro the above weight heavily against me.
As a diyer you might well find that some descaler (DS3, patio cleaner,
kill roc etc.) does the business.
It is academic which side is the main culprit as once it's in the acid
both sides will be fixed.

All the best

HTH
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

"Martin Pentreath" wrote in message
...
On 7 May, 14:34, "Doctor Drivel" wrote:
"Mathew Newton" wrote in message

...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.

I have to do this job periodically on my Ariston Microgenus. Speaking
as a tight-fisted southerner it's definitely worth it, and I remember
the joy throughout the household the first time I did it and restored
full flow and heat to the shower! Ah the rewards of DIY.

Anyway, I agree with Drivel that DS3 is the stuff for descaling.
However, sometimes in my case the clogging is on the primary side due
to iron oxide (rather than limescale on the secondary side). In this
case I don't know of any chemicals which will shift it, and it's just
a matter of flushing it through at as high a pressure as you can
manage, coupled with some knocking about to dislodge stuff. By the
way, I find a cheap drill-attachment pump with a couple of suitable
bits of hose is good for circulating hot DS3 solution through the heat
exchanger.

If it is black iron oxide causing the problem then you don't have
enough inhibitor in the system, and the whole system will need a flush
through and fresh inhibitor.

I've managed to keep mine going for the last five years like this.
It's a couple of hours work, most of which is just leaving it soaking.

Cheers!

Martin


Where are you in the south to get so much scale?
Best fit a Magnaclean and do what I said regarding cleaning.

On 7 May, 17:47, Ed Sirett wrote:

It is academic which side is the main culprit as once it's in the acid
both sides will be fixed.

Hi Ed, is this right? I've never found DS3 (or any other chemical)
dissolves iron oxide, which is the main culprit on the primary side.
'A' level chemistry is a long way off now, but I think it's not easy
stuff to remove chemically.

Cheers,

Martin

On May 7, 5:28 pm, Martin Pentreath
wrote:
Speaking
as a tight-fisted southerner it's definitely worth it,

Ahh... perhaps we're not all that different after all! ;-)

and I remember
the joy throughout the household the first time I did it and restored
full flow and heat to the shower! Ah the rewards of DIY.

Now you're talking - that's what I like to hear. Your positive
experience has convinced me to at least give it a shot.

Ed's mention of downtime and leak potential are valid points but the
GF has been reminded she has showers at work, and if the heat
exchanger springs a leak I will convince myself it was about to happen
anyway and hence justify the £90 for a new one. Regarding o-rings and
fibre washers I've got a pack of the former so will get the latter
also to be on the safe side (the official WB part/bag is around £7.50
- are they really that special or will any generic bag of suitably
sized fibre washers suffice?)

Anyway, I agree with Drivel that DS3 is the stuff for descaling.
However, sometimes in my case the clogging is on the primary side due
to iron oxide (rather than limescale on the secondary side). In this
case I don't know of any chemicals which will shift it, and it's just
a matter of flushing it through at as high a pressure as you can
manage, coupled with some knocking about to dislodge stuff. By the
way, I find a cheap drill-attachment pump with a couple of suitable
bits of hose is good for circulating hot DS3 solution through the heat
exchanger.

B&Q sell Fernox DS3 by the small tub for £3 so it's worth a shot with
that anyway. As for the drill pump I'll give that a go also - tight
fistedness is overruled by opportunities to buy new tools so I'll pick
one up from Machine Mart (£13 and stainless steel innards so should
last me a while).

If it is black iron oxide causing the problem then you don't have
enough inhibitor in the system, and the whole system will need a flush
through and fresh inhibitor.

Yeah I'll put some fresh. The system has been topped up a few times
over the years during radiator removals etc so it could probably
benefit from some.

I've managed to keep mine going for the last five years like this.
It's a couple of hours work, most of which is just leaving it soaking.

Finger's crossed...

I may find it's not bunged up at all in which case I can then focus on
buying a new diverter valve instead!

Mathew

"Martin Pentreath" wrote in message
...
On 7 May, 17:47, Ed Sirett wrote:

It is academic which side is the main culprit as once it's in the acid
both sides will be fixed.

Hi Ed, is this right? I've never found DS3 (or any other chemical)
dissolves iron oxide, which is the main culprit on the primary side.
'A' level chemistry is a long way off now, but I think it's not easy
stuff to remove chemically.

Cheers,

Martin

If you are talking about rust, (iron oxide?), then Muriatic Acid ( AKA
hydrochloric Acid ) will strip rust from steel/iron.
I don't know what your heat exchanger is made of so don't blame me if it
full of holes after this treatment !
A form of Muriatic acid is sold in builders merchants as Brick Cleaner if
you want to give it a try.
I have used this, cold, on bits of rusty steel from an outboard motor with
good results.

Ian.

On 7 May, 22:59, "Ian French" wrote:

If you are talking about rust, (iron oxide?), then Muriatic Acid ( AKA
hydrochloric Acid ) will strip rust from steel/iron.
I don't know what your heat exchanger is made of so don't blame me if it
full of holes after this treatment !
A form of Muriatic acid is sold in builders merchants as Brick Cleaner if
you want to give it a try.
I have used this, cold, on bits of rusty steel from an outboard motor with
good results.

Ian.

Hi Ian,

Again, stretching my recollection of schoolboy chemistry here, but the
black stuff you get in heating systems is iron I oxide, brown rust is
iron III oxide. What the difference is I forget, but I think the black
stuff is harder to dissolve.

Matthew, I can conclusively prove that southerners are more tight-
fisted than northerners. I've always used the same O rings without a
problem (never occurred to me to get new ones, do you think I'm made
of money?) and I got a drill pump from Toolstation for a fiver (part
number 23710). Good luck with the boiler.

Cheers!

Martin

Martin Pentreath wrote:
On 7 May, 22:59, "Ian French" wrote:

If you are talking about rust, (iron oxide?), then Muriatic Acid ( AKA
hydrochloric Acid ) will strip rust from steel/iron.
I don't know what your heat exchanger is made of so don't blame me if it
full of holes after this treatment !
A form of Muriatic acid is sold in builders merchants as Brick Cleaner if
you want to give it a try.
I have used this, cold, on bits of rusty steel from an outboard motor with
good results.

Ian.

Hi Ian,

Again, stretching my recollection of schoolboy chemistry here, but the
black stuff you get in heating systems is iron I oxide, brown rust is
iron III oxide. What the difference is I forget, but I think the black
stuff is harder to dissolve.

Matthew, I can conclusively prove that southerners are more tight-
fisted than northerners. I've always used the same O rings without a
problem (never occurred to me to get new ones, do you think I'm made
of money?) and I got a drill pump from Toolstation for a fiver (part
number 23710). Good luck with the boiler.

Cheers!

Martin

I dont have any answers to offer on this, just a couple of points
that
might possibly be worth looking up. Oxalic acid is used to remove
rust stains, and rust convertors are usually phosphoric acid based.


NT

On 7 May, 23:42, Martin Pentreath
wrote:

Matthew, I can conclusively prove that southerners are more tight-
fisted than northerners. I've always used the same O rings without a
problem (never occurred to me to get new ones, do you think I'm made
of money?) and I got a drill pump from Toolstation for a fiver (part
number 23710). Good luck with the boiler.

Hmm... Now you've made me look all flash throwing my money around. I
did see the Toolstation one but figured that long term I might be
better off with the more substantial MM version (http://tinyurl.com/
4ahouj) - at least it's got some specs that sound good. You get what
you pay for right? Whoa.. the sun has clearly got to me. Maybe I'll
call in to TS and have a closer look.

Mathew

In article ,
Stuart Noble writes:
Doctor Drivel wrote:

Fernox DS3 to descale. DS = Descale.


A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
put the acid back (or a fresh lot)

No they won't work. The volume of scale which builds up in a
blocked plate exchanger way exceeds what you find in a kettle.
A tub of DS3 will be much cheaper than the quantity of kettle
descaler you would require, and it's not mixed with sand and
other things used to bulk out kettle descaler which you don't
want in a heating system, and it contains a colour change
indicator so you know when the mix needs to be replaced.

You can use DS3 around the house for other descaling purposes,
but not on plastics (it makes some plastics go brittle).

I think the danger is that the crud may be masking leaks, which might
start to flow freely once the corrosion has gone.
I remember descaling a rad on an old Morris Minor once (anti freeze
wasn't standard back then). It functioned perfectly for a few days, and
then the bottom fell out

The bottoms fell out of lots of Morris Minor's. I know someone
who is still keeping one going (last time I bumped into him
anyway). If you see a Morris Minor with a penny farthing bicycle
rack driving along, I doubt there's more than one in existence.

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

"Martin Pentreath" wrote in message
...
On 7 May, 22:59, "Ian French" wrote:

If you are talking about rust, (iron oxide?), then Muriatic Acid ( AKA
hydrochloric Acid ) will strip rust from steel/iron.
I don't know what your heat exchanger is made of so don't blame me if it
full of holes after this treatment !
A form of Muriatic acid is sold in builders merchants as Brick Cleaner if
you want to give it a try.
I have used this, cold, on bits of rusty steel from an outboard motor
with
good results.

Ian.

Hi Ian,

Again, stretching my recollection of schoolboy chemistry here, but the
black stuff you get in heating systems is iron I oxide, brown rust is
iron III oxide. What the difference is I forget, but I think the black
stuff is harder to dissolve.

Matthew, I can conclusively prove that southerners are more tight-
fisted than northerners. I've always used the same O rings without a
problem (never occurred to me to get new ones, do you think I'm made
of money?) and I got a drill pump from Toolstation for a fiver (part
number 23710). Good luck with the boiler.

Cheers!

Martin

Hi Martin,

Yes, on reflection, what you need is EVAPORUST !

No, I am not joking, see this link
http://www.evapo-rust.co.nz/How%20It%20Works.htm

Ian.

Doctor Drivel wrote:

"Stuart Noble" wrote in message
...
Doctor Drivel wrote:

"Mathew Newton" wrote in message
...
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water) heat exchanger in my WB
24CDi combi.

Given the potential uncertainty surrounding the fault/cure, and the
fact that I am a tight Northerner, I was wondering about ways to avoid/
delay the £90 expenditure on a new heat exchanger.

In particular, I wondered about removing the heat exchanger and at the
very least checking and testing it - but also perhaps cleaning/
unblocking it too. Any tips/suggestions/ideas as the ways to go about
this? I am assuming it will require more than physical cleansing,
perhaps chemical cleansing to really dislodge any crud in there so I
was wondering what I should get and from where?

Feel free to tell me to blow the dust of my wallet if this skimping is
really not worth the hassle (the boiler, and heat exchanger, is 11
years old by the way).

Mathew


Fernox DS3 to descale. DS = Descale.

A couple of packs of supermarket kettle descaler would probably work as
well if you're really tight. Leave overnight drain flush with a hose
put the acid back (or a fresh lot)
I think the danger is that the crud may be masking leaks, which might
start to flow freely once the corrosion has gone.
I remember descaling a rad on an old Morris Minor once (anti freeze
wasn't
standard back then). It functioned perfectly for a few days, and then the
bottom fell out

Plate heat exchangers are stainless steel.
The heat exchanger is probably a stainles steel plate heat exchanger (HX).
Dowload service manual from the WB site for you model and check.
Check it isn't a failed water pressure or temperature sensor
If it is a sceled up HX then you could do this yourself - no gas
connections involved.

Find the right fittings for the HX connectors, both primary and
secondary side.

Take the HX out, connect rubber hoze to HX inlets, outlets and see if
water flows through

Go to a DIY and butuy a small tub of sulphamic acid descaler (powder)
such as Fernox DS-3 or similar. Citric acid descalers are less vigorous
and very slow on lime scale ( but less harmful top plastic kettles etc)

Follow instructions - best used hot as reaction is faster, and rig up
some form of small break tank and pump. thgis is to ensure fresh acid
keeps passing through the heaat exchanger.

Do this outside - and well ventialted area and follow H&S precuations (
eye protection, rubber gloves etc) & common sense , no peets kids etc
nearby etc.

FWIW

On May 8, 5:53 pm, rdd wrote:

Check it isn't a failed water pressure or temperature sensor

The CH flow pipe is heating up also so I've narrowed it down to a
sticking diverter, or blocked heat-exchanger (on the basis that this
could cause divert bypass).

If it is a sceled up HX then you could do this yourself - no gas
connections involved.

Yeah, I'm going to give it a go and whilst it's off I'm hoping I can
get a finger inside a divert valve port and manually move the slider.

Find the right fittings for the HX connectors, both primary and
secondary side.

Take the HX out, connect rubber hoze to HX inlets, outlets and see if
water flows through

Go to a DIY and butuy a small tub of sulphamic acid descaler (powder)
such as Fernox DS-3 or similar. Citric acid descalers are less vigorous
and very slow on lime scale ( but less harmful top plastic kettles etc)

Follow instructions - best used hot as reaction is faster, and rig up
some form of small break tank and pump. thgis is to ensure fresh acid
keeps passing through the heaat exchanger.

I'm all good to go on this. Got the descaler, pump and bits+bobs.

Thank you, and everyone, for the help. Will report back how it goes!

Mathew

On Wed, 07 May 2008 15:42:30 -0700, Martin Pentreath wrote:

On 7 May, 22:59, "Ian French" wrote:

If you are talking about rust, (iron oxide?), then Muriatic Acid ( AKA
hydrochloric Acid ) will strip rust from steel/iron. I don't know what
your heat exchanger is made of so don't blame me if it full of holes
after this treatment !
A form of Muriatic acid is sold in builders merchants as Brick Cleaner
if you want to give it a try.
I have used this, cold, on bits of rusty steel from an outboard motor
with good results.

Ian.

Hi Ian,

Again, stretching my recollection of schoolboy chemistry here, but the
black stuff you get in heating systems is iron I oxide, brown rust is
iron III oxide. What the difference is I forget, but I think the black
stuff is harder to dissolve.

Matthew, I can conclusively prove that southerners are more tight-
fisted than northerners. I've always used the same O rings without a
problem (never occurred to me to get new ones, do you think I'm made of
money?) and I got a drill pump from Toolstation for a fiver (part number
23710). Good luck with the boiler.

Cheers!

Martin

The particles tend to be an mixture of both Black Oxide (which will need
quite strong acid to reduce) and scale which HCl easily removes.

In my experience there is enough frothing on the primary side of a DHW to
mean that using the acid is worth while.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

[Posted from google since ntl's newsserver seems to be currently
pantsed]

On 7 May, 19:57, Martin Pentreath
wrote:

Hi Ed, is this right? I've never found DS3 (or any other chemical)
dissolves iron oxide, which is the main culprit on the primary side.
'A' level chemistry is a long way off now, but I think it's not easy
stuff to remove chemically.

If Ed's right about the flakes being a mixture of chalk (scale) and
iron
oxides then acid should break it down. Chemicals are your best
chance: pressure flushing will probably be relatively ineffective
since
once there's a passageway through the heat exchanger the flow will
go through that leaving other parallel passageways blocked.

On May 8, 6:41 pm, Ed Sirett wrote:

The particles tend to be an mixture of both Black Oxide (which will need
quite strong acid to reduce) and scale which HCl easily removes.

In my experience there is enough frothing on the primary side of a DHW to
mean that using the acid is worth while.

For what it's worth I noticed that the Fernox DS3 is actually
'Sulphamic Acid' - I see various mentions of it on t'web saying it is
suitable for rust removal as well as scale so I've got high hopes!

Mathew

Mathew Newton wrote:
On May 8, 6:41 pm, Ed Sirett wrote:

The particles tend to be an mixture of both Black Oxide (which will need
quite strong acid to reduce) and scale which HCl easily removes.

In my experience there is enough frothing on the primary side of a DHW to
mean that using the acid is worth while.

For what it's worth I noticed that the Fernox DS3 is actually
'Sulphamic Acid' - I see various mentions of it on t'web saying it is
suitable for rust removal as well as scale so I've got high hopes!

Mathew

I keep a tub of 10% diluted to stick the shower head in.
I think the advantage with sulphamic is that it's a strong acid but is
easy to handle, with no fumes

On May 7, 2:21 pm, Mathew Newton wrote:
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water)heatexchangerin my WB
24CDi combi.

Hmm... Took the heat exchanger to clean out today....

Unfortunately the last couple of days have been okay for HW - the CH
flow pipe is still getting hot but the HW is a stable at a hot
temperature. Bloody typical of course as it means it's hard to see if
I've fixed things... but the hot CH flow pipe is a persistent issue so
I guess that's the indicator.

I took the heat exchanger out and found it was actually pretty clean -
the secondary side seemed spotless in fact, and the primary rather
black. A few hose-throughs brought out quite a bit of black flakes...
pictures below...

http://www.newtonnet.co.uk/house/boiler/heatexchanger/

There wasn't much though, and indeed the inline strainer pictured
hardly had anything in it (and the CH water was a darkish yellow...
not brown and certainly not black).

I pumped through some DS3 and this got rid a lot of the stuff and I'm
sure the flow through it with the hose seemed to improve.

So.... I put it all back together again and, unbelievably given the WB
CDi series is designed to spring a leak following any work on it, got
a watertight assembly first time!

A HW demand however still produced a hot CH flow pipe.... but didn't
cut out at all (although as mentioned is hasn't the last couple of
days anyway). I'm sure the shower feels better (hotter at higher flow)
but whilst this may be psychological the cleaning out must've helped.

So now I'm thinking it's the divert valve sticking. Given the price I
may just fit a new one - I don't fancy taking mine out to inspect/
clean, particularly if it is beyond repair.

Any thoughts from your guys would most welcome again.... I wondered if
some cleaner (X300?) in the system might help free the diverter up (if
it is indeed sticking or not moving far enough)...? The primary heat
exchanger sounds like it's heading towards kettling at some time in
the not-too-distant future so maybe this would be a good double-
whammy.

Hey, at least the sun is shining and the boiler still 'works'... ;-)

Mathew

"Mathew Newton" wrote in message
...
On May 7, 2:21 pm, Mathew Newton wrote:
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water)heatexchangerin my WB
24CDi combi.

Hmm... Took the heat exchanger to clean out today....

Unfortunately the last couple of days have been okay for HW - the CH
flow pipe is still getting hot but the HW is a stable at a hot
temperature. Bloody typical of course as it means it's hard to see if
I've fixed things... but the hot CH flow pipe is a persistent issue so
I guess that's the indicator.

I took the heat exchanger out and found it was actually pretty clean -
the secondary side seemed spotless in fact, and the primary rather
black. A few hose-throughs brought out quite a bit of black flakes...
pictures below...

http://www.newtonnet.co.uk/house/boiler/heatexchanger/

There wasn't much though, and indeed the inline strainer pictured
hardly had anything in it (and the CH water was a darkish yellow...
not brown and certainly not black).

I pumped through some DS3 and this got rid a lot of the stuff and I'm
sure the flow through it with the hose seemed to improve.

So.... I put it all back together again and, unbelievably given the WB
CDi series is designed to spring a leak following any work on it, got
a watertight assembly first time!

A HW demand however still produced a hot CH flow pipe.... but didn't
cut out at all (although as mentioned is hasn't the last couple of
days anyway). I'm sure the shower feels better (hotter at higher flow)
but whilst this may be psychological the cleaning out must've helped.

So now I'm thinking it's the divert valve sticking. Given the price I
may just fit a new one - I don't fancy taking mine out to inspect/
clean, particularly if it is beyond repair.

Any thoughts from your guys would most welcome again.... I wondered if
some cleaner (X300?) in the system might help free the diverter up (if
it is indeed sticking or not moving far enough)...? The primary heat
exchanger sounds like it's heading towards kettling at some time in
the not-too-distant future so maybe this would be a good double-
whammy.

Cleaning out the system is well worth it, while you are at it. Kettling
sounds may be the giveaway clue. Try Fernox cleaner as it is more acidic.
Flush and add X-100.

On Sun, 11 May 2008 08:39:45 -0700, Mathew Newton wrote:

On May 7, 2:21 pm, Mathew Newton wrote:
A recent thread of mine on here led to the probable diagnosis of a
scaled/blocked secondary (water-to-water)heatexchangerin my WB 24CDi
combi.

Hmm... Took the heat exchanger to clean out today....

Unfortunately the last couple of days have been okay for HW - the CH
flow pipe is still getting hot but the HW is a stable at a hot
temperature. Bloody typical of course as it means it's hard to see if
I've fixed things... but the hot CH flow pipe is a persistent issue so I
guess that's the indicator.

I took the heat exchanger out and found it was actually pretty clean -
the secondary side seemed spotless in fact, and the primary rather
black. A few hose-throughs brought out quite a bit of black flakes...
pictures below...

http://www.newtonnet.co.uk/house/boiler/heatexchanger/

There wasn't much though, and indeed the inline strainer pictured hardly
had anything in it (and the CH water was a darkish yellow... not brown
and certainly not black).

I pumped through some DS3 and this got rid a lot of the stuff and I'm
sure the flow through it with the hose seemed to improve.

So.... I put it all back together again and, unbelievably given the WB
CDi series is designed to spring a leak following any work on it, got a
watertight assembly first time!

A HW demand however still produced a hot CH flow pipe.... but didn't cut
out at all (although as mentioned is hasn't the last couple of days
anyway). I'm sure the shower feels better (hotter at higher flow) but
whilst this may be psychological the cleaning out must've helped.

So now I'm thinking it's the divert valve sticking. Given the price I
may just fit a new one - I don't fancy taking mine out to inspect/
clean, particularly if it is beyond repair.

Any thoughts from your guys would most welcome again.... I wondered if
some cleaner (X300?) in the system might help free the diverter up (if
it is indeed sticking or not moving far enough)...? The primary heat
exchanger sounds like it's heading towards kettling at some time in the
not-too-distant future so maybe this would be a good double- whammy.

Hey, at least the sun is shining and the boiler still 'works'... ;-)

Mathew

Does the CH pipe heat up after the HW has been run or whilst the HW is
running? The former this is normal operation.
It is also possible that the DHW flow diaphragm is not pushing the
diverter valve 100% is it has a small split in it.
I doubt X300/X400 will improve things.

The leakage into the CH might only be a few percent and possibly the cure
is worse than the condition?








--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On May 11, 7:37 pm, Ed Sirett wrote:

Does the CH pipe heat up after the HW has been run or whilst the HW is
running? The former this is normal operation.

It occurs during HW operation (as well as post-HW on occasion as is
correct behaviour as you say).

It is also possible that the DHW flow diaphragm is not pushing the
diverter valve 100% is it has a small split in it.

The diaphragm is moving sufficiently far to fully activate the
microswitch.. And I think I am right in saying that on this diverter
the diaphragm doesn't actually move the diverter but rather
effectively moves out of the way to allow the diverter innards to
slide across/out (presumably under force from the flow in the
primary). I say this because when I replaced the diaphragm a few years
ago (d'oh - should've done the whole valve!) I noticed there the only
contact between the diaphragm and diverter cylinder was the head of
the diaphragm rod i.e. it could push the diverter cylinder, or stop it
moving, but couldn't pull it (if you see what I mean).

I doubt X300/X400 will improve things.

The leakage into the CH might only be a few percent and possibly the cure
is worse than the condition?

Yeah I guess... certainly if the HW operation remains stable as it is
at the moment then I could probably ignore it... either in the hope
that it will go away or until a new valve pops up on eBay for next-to-
nothing which seems to happen on occasion.

The other part of me is wondering how much life this boiler has got
left in it... for a 'modern' boiler it's probably not doing too bad
for 11 years and not having much wrong with it along the way.

Mathew

On Sun, 11 May 2008 12:19:26 -0700, Mathew Newton wrote:

On May 11, 7:37 pm, Ed Sirett wrote:

Does the CH pipe heat up after the HW has been run or whilst the HW is
running? The former this is normal operation.

It occurs during HW operation (as well as post-HW on occasion as is
correct behaviour as you say).

It is also possible that the DHW flow diaphragm is not pushing the
diverter valve 100% is it has a small split in it.

The diaphragm is moving sufficiently far to fully activate the
microswitch.. And I think I am right in saying that on this diverter the
diaphragm doesn't actually move the diverter but rather effectively
moves out of the way to allow the diverter innards to slide across/out
(presumably under force from the flow in the primary). I say this
because when I replaced the diaphragm a few years ago (d'oh - should've
done the whole valve!) I noticed there the only contact between the
diaphragm and diverter cylinder was the head of the diaphragm rod i.e.
it could push the diverter cylinder, or stop it moving, but couldn't
pull it (if you see what I mean).

IIRC there is bloddy great spring inside the diverter valve which moves
it back to the start.



I doubt X300/X400 will improve things.

The leakage into the CH might only be a few percent and possibly the
cure is worse than the condition?

Yeah I guess... certainly if the HW operation remains stable as it is at
the moment then I could probably ignore it... either in the hope that it
will go away or until a new valve pops up on eBay for next-to- nothing
which seems to happen on occasion.

The other part of me is wondering how much life this boiler has got left
in it... for a 'modern' boiler it's probably not doing too bad for 11
years and not having much wrong with it along the way.

Mathew

For a quality make like WB 11 years should only be mid-life. However all
combis of this generic design from all the makes seems to perform worse
than C21 models.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On May 12, 8:55 pm, Ed Sirett wrote:

IIRC there is bloddy great spring inside the diverter valve which moves
it back to the start.

There is - but the start is CH mode!

For a quality make like WB 11 years should only be mid-life. However all
combis of this generic design from all the makes seems to perform worse
than C21 models.

I did wonder - maybe I'll keep it going for a wee while yet then. By
the way, what's 'C21'?

Incidentally, I cannot help feel that the 24CDi was not designed to be
easily repaired - it feels like open heart surgery to work on
practically anything within it. Is this normal? I'm wondering if there
are any boilers out there that are a little more DIY-friendly as
whilst I get satisfaction from repairing this one I don't particularly
appreciate removing perfectly good parts just to get at what I'm
trying to fix... and I always hold my breath having reassembled it...

Perhaps I'd be better off with a non-combi next time as whilst I may
have to find space for the external gubbins the slight avoidance of
the 'eggs in one basket' aspect is appealing... oh how I dream of
having a nice simple immersion heater as backup!

Mathew

"Mathew Newton" wrote in message
...
On May 12, 8:55 pm, Ed Sirett wrote:

IIRC there is bloddy great spring inside the diverter valve which moves
it back to the start.

There is - but the start is CH mode!

For a quality make like WB 11 years should only be mid-life. However all
combis of this generic design from all the makes seems to perform worse
than C21 models.

I did wonder - maybe I'll keep it going for a wee while yet then. By
the way, what's 'C21'?

Incidentally, I cannot help feel that the 24CDi was not designed to be
easily repaired - it feels like open heart surgery to work on
practically anything within it. Is this normal? I'm wondering if there
are any boilers out there that are a little more DIY-friendly as
whilst I get satisfaction from repairing this one I don't particularly
appreciate removing perfectly good parts just to get at what I'm
trying to fix... and I always hold my breath having reassembled it...

Perhaps I'd be better off with a non-combi next time as whilst I may
have to find space for the external gubbins the slight avoidance of
the 'eggs in one basket' aspect is appealing... oh how I dream of
having a nice simple immersion heater as backup!

Look at an Atmos. The pressure vessel hinges out of the way. A dream to work
on. The best designed combi around. They just don't go wrong.
http://www.atmos.uk.com/product_grou...n=000200130003

"Mathew Newton" wrote in message
...

oh how I dream of
having a nice simple immersion heater as backup!

In the outlet of the copmbi install a 9kW instant eclectic heater. This is
small and can be under the sink. Have it off and the combi hot water just
runs through it. If the combi is down then switch on. Simple. It will do a
shower and even two taps at the same time. Or buy an Atmos combi - they
don't go wrong.

Doctor Drivel wrote:
snip
Look at an Atmos. The pressure vessel hinges out of the way. A dream to
work on. The best designed combi around. They just don't go wrong.
http://www.atmos.uk.com/product_grou...n=000200130003

Obviously didn't see Doctor Who the other week. :-)

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

On Mon, 12 May 2008 14:26:32 -0700, Mathew Newton wrote:

On May 12, 8:55 pm, Ed Sirett wrote:

IIRC there is bloddy great spring inside the diverter valve which moves
it back to the start.

There is - but the start is CH mode!

Yep.


For a quality make like WB 11 years should only be mid-life. However
all combis of this generic design from all the makes seems to perform
worse than C21 models.

I did wonder - maybe I'll keep it going for a wee while yet then. By the
way, what's 'C21'?

21st Century.


Incidentally, I cannot help feel that the 24CDi was not designed to be
easily repaired - it feels like open heart surgery to work on
practically anything within it. Is this normal? I'm wondering if there
are any boilers out there that are a little more DIY-friendly as whilst
I get satisfaction from repairing this one I don't particularly
appreciate removing perfectly good parts just to get at what I'm trying
to fix... and I always hold my breath having reassembled it...

Perhaps I'd be better off with a non-combi next time as whilst I may
have to find space for the external gubbins the slight avoidance of the
'eggs in one basket' aspect is appealing... oh how I dream of having a
nice simple immersion heater as backup!

No idea.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On 2008-05-13 11:22:24 +0100, Rod said:

Doctor Drivel wrote:
snip
Look at an Atmos. The pressure vessel hinges out of the way. A dream to
work on. The best designed combi around. They just don't go wrong.
http://www.atmos.uk.com/product_grou...n=000200130003

Obviously didn't see Doctor Who the other week. :-)

Yes, but it says it in the data sheet so it must be right.

"Andy Hall" wrote in message news:482f11df@qaanaaq...
On 2008-05-13 11:22:24 +0100, Rod said:

Doctor Drivel wrote:
snip
Look at an Atmos. The pressure vessel hinges out of the way. A dream to
work on. The best designed combi around. They just don't go wrong.
http://www.atmos.uk.com/product_grou...n=000200130003

Obviously didn't see Doctor Who the other week. :-)

Yes, but it says it in the data sheet so it must be right.

Matt, Dr Who is always right?