My mother telephoned today to say that the heating engineer had called to
identify her hot water problem with her combi and they had told her that her
Heat Exchanger had furred. I haven't the make or model number for the combi
but I don't think it really matters as most combi work on a similar
principle (?) that they heat hot water for the central heating/radiators on
one system and the heating of the hot water is a separate system and both
systems are contained within the combi.

The query my mother has raised is that the heating engineer has said that
she needs a Magnaclean filter fitting to stop the hot water heat exchanger
furring up again. If she doesn't have one fitted then, whilst they'll fix
the heat exchanger with a sonic cleanse this time, they'll charge her if it
furrs up again. He can fit one for a round £200. To me the Magnaclean will
only stop the sludging of the radiators of the central heating and will have
no effect what-so-ever on the heat exchanger ... am I right?

As I'm relaying this story third party I'd rather not say which well known
and national company my mother has a maintenance contract with just in case
she's got some wires crossed somewhere (which I doubt). To me the
requirement to fit a Magnaclean, whilst good advice for the central
heating/radiators, has nothing to do with the fault and smacks of sharp
sales practice and someone wanting to boost their sales bonus.

Any thoughts?

Ash

Ash wrote:
most combi work on a similar principle (?) that they heat hot water
for the central heating/radiators on one system and the heating of
the hot water is a separate system and both systems are contained
within the combi.

The two water paths are separate, but they're not completely independent
systems. To heat hot water, the "central heating" water is heated by the
gas and then, instead of going round the radiator circuit, it's diverted
through a heat exchanger to transfer its heat to the hot water side.

The query my mother has raised is that the heating engineer has said
that she needs a Magnaclean filter fitting to stop the hot water heat
exchanger furring up again.
[...]
To me the Magnaclean will only stop the sludging of the radiators of
the central heating and will have no effect what-so-ever on the heat
exchanger ... am I right?

Depends on what the actual problem with the heat exchanger was. If it
was blocked on the hot-water side then the filter seems unlikely to help
(unless there's some odd effect where sludge in the other side causes
less-even heating and consequent problems). If it was blocked on the
other side, which is actually part of the central heating water, then a
magnaclean doesn't seem unreasonable.

Pete

John Rumm wrote:
Ash wrote:

My mother telephoned today to say that the heating engineer had
called to identify her hot water problem with her combi and they had
told her that her Heat Exchanger had furred. I haven't the make or
model number for the combi but I don't think it really matters as
most combi work on a similar principle (?) that they heat hot water
for the central heating/radiators on one system and the heating of
the hot water is a separate system and both systems are contained
within the combi.

It might be worth checking the make and model, since although you are
correct that the majority of combis work on the same principle, there
are a few that deviate from the norm.

The query my mother has raised is that the heating engineer has said
that she needs a Magnaclean filter fitting to stop the hot water
heat exchanger furring up again. If she doesn't have one fitted
then, whilst they'll fix the heat exchanger with a sonic cleanse
this time, they'll charge her if it furrs up again. He can fit one
for a round £200. To me the Magnaclean will only stop the sludging
of the radiators of the central heating and will have no effect
what-so-ever on the heat exchanger ... am I right?

Probably. If by "furred" they mean the HW HE was obstructed by hard
water scale on the domestic hard water side, then you are right - the
magnaclean will have no effect. If they mean the HE was blocked on the
primary flow side by sludge, then it may help. (although fixing why
the primary side is sludging up in the first place would be better
than trying to treat the symptom).

As I'm relaying this story third party I'd rather not say which well
known and national company my mother has a maintenance contract with
just in case

British gas then ;-)

Spooky - I thought the very same :-) Bunch of bandits IMO.. At least Dick
Turpin had the decency to wear a mask...


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Fri, 30 Oct 2009 15:41:56 +0000, Ash wrote:

My mother telephoned today to say that the heating engineer had called to
identify her hot water problem with her combi and they had told her that her
Heat Exchanger had furred. I haven't the make or model number for the combi
but I don't think it really matters as most combi work on a similar
principle (?) that they heat hot water for the central heating/radiators on
one system and the heating of the hot water is a separate system and both
systems are contained within the combi.

No, the type you describe was always relatively uncommon and AFAIK no-one
makes that type any more (i.e. as high-efficiency/condensing boilers).
Much more common is the arrangement whereby the primary gas-water heat
exchanger heats water that goes either to the central heating or to a
secondary heat exchanger that heats the hot water. These secondary heat
exchangers are usually plate types (PHEs) and these are susceptible to
scaling ('furring') up on the secondary, domestic hot water, side, or to
getting blocked up with gritty magnetic debris on the primary side from
the water that also goes round the radiators. In my limited experience of
this phenomenon it seems to be Baxi Combi 80 or 100s and Potterton
Performas (same model, different badge) which are susceptible.



The query my mother has raised is that the heating engineer has said that
she needs a Magnaclean filter fitting to stop the hot water heat exchanger
furring up again.

Sounds like a good idea. However I fitted a Fernox Boiler Buddy (similar
idea - magnetic filter) to one of my victim machines and its PHE still got
blocked! A quick swish round the system with the powerflushing machine
bought several months' trouble-free operation but the problem eventually
recurred. Fortunately with these boilers one can swap the PHEs in a matter
of a few minutes, and Norstrom (who make my flushing machine) do an
adaptor specifically for power-flushing these PHEs (I wonder what that
tells us about them!). So now I keep a cleaned one in the van and swap it
for the one in each latest victim boiler as I come across them!


If she doesn't have one fitted then, whilst they'll
fix the heat exchanger with a sonic cleanse this time,

Interested to know what a 'sonic cleanse' is.

... To
me the requirement to fit a Magnaclean, whilst good advice for the
central heating/radiators, has nothing to do with the fault and smacks
of sharp sales practice and someone wanting to boost their sales bonus.

I think Magnaclean-type devices aren't for protecting radiators so much as
protecting the narrow waterways in boilers' heat exchangers - including
the primary gas-water heat exchangers in modern boilers.

Any thoughts?

I think your mother's engineers may be making an honest and sensible
attempt to deal with a problem not just immediately but in the long term.


--
John Stumbles -- http://yaph.co.uk

Many hands make light work. Too many cooks spoil the broth.

No, the type you describe was always relatively uncommon and AFAIK no-one
makes that type any more (i.e. as high-efficiency/condensing boilers).
Much more common is the arrangement whereby the primary gas-water heat
exchanger heats water that goes either to the central heating or to a
secondary heat exchanger that heats the hot water. These secondary heat
exchangers are usually plate types (PHEs) and these are susceptible to
scaling ('furring') up on the secondary, domestic hot water, side, or to
getting blocked up with gritty magnetic debris on the primary side from
the water that also goes round the radiators. In my limited experience of
this phenomenon it seems to be Baxi Combi 80 or 100s and Potterton
Performas (same model, different badge) which are susceptible.


Checked again with my mother and it's a Ideal Boiler HE30 and yes your
correct it's got a Plate Heat Exchanger .. (accordingly to the manual she
has).

If she doesn't have one fitted then, whilst they'll
fix the heat exchanger with a sonic cleanse this time,

Interested to know what a 'sonic cleanse' is.

We're not sure what a sonic cleanse is also ... perhaps some sort of ray gun
8-( ?

Looks like we'll be waiting a while ... they've booked her in for 14th
November to come and do the repairs. She's in her 70's and they consider it
reasonable to let her wait over two weeks before she can have a bath. I
think a nice strong phone call is in order first thing in the morning.

Ash wrote:
No, the type you describe was always relatively uncommon and AFAIK
no-one makes that type any more (i.e. as high-efficiency/condensing
boilers). Much more common is the arrangement whereby the primary
gas-water heat exchanger heats water that goes either to the
central heating or to a secondary heat exchanger that heats the hot
water. These secondary heat exchangers are usually plate types
(PHEs) and these are susceptible to scaling ('furring') up on the
secondary, domestic hot water, side, or to getting blocked up with
gritty magnetic debris on the primary side from the water that also
goes round the radiators. In my limited experience of this
phenomenon it seems to be Baxi Combi 80 or 100s and Potterton
Performas (same model, different badge) which are susceptible.

Checked again with my mother and it's a Ideal Boiler HE30 and yes your
correct it's got a Plate Heat Exchanger .. (accordingly to the manual
she has).

If she doesn't have one fitted then, whilst they'll
fix the heat exchanger with a sonic cleanse this time,

Interested to know what a 'sonic cleanse' is.

We're not sure what a sonic cleanse is also ... perhaps some sort of
ray gun 8-( ?

Looks like we'll be waiting a while ... they've booked her in for 14th
November to come and do the repairs. She's in her 70's and they
consider it reasonable to let her wait over two weeks before she can
have a bath. I think a nice strong phone call is in order first thing
in the morning.

As good as ever a reason for not having a combi boiler. With a DHW cylinder
and an immersion heater she would still have had hot water at least.

Interested to know what a 'sonic cleanse' is.

We're not sure what a sonic cleanse is also ... perhaps some sort of ray
gun 8-( ?

I imagine it's an ultrasonic cleaner, which could well help.

I had the primary (i.e. the closed loop) of my DHW (on a Halstead combi)
block last year with the usual black sludge and debris, corrosion products
from radiators because of insufficient inhibition. Replaced the heat
exchanger and put in a Magnaclean (and added inhibitor). Within about six
months it was misbehaving again. The Magnaclean had certainly trapped a fair
amount of black oxide, but the heat exchange primary was blocked again. This
time I tried a chemical clean on the removed heat exchanger using formic
acid (kettle descaler) plus flushing. Not the ideal chemical approach,
hydrochloric acid (brick acid) would be better but this can be bad for
stainless steel heat exchangers. It's been OK for a while; perhaps the
Magnaclean is taking a while to collect the existing circuit debris. In an
ideal world you might flush and re-dose the whole circuit, but that wasn't
practicable for me at the time. There doesn't seem to be a problem with
limescale buildup on the secondary (domestic hot water) side in my system; I
don't think the heat exchanger really runs hot enough.

I'm reasonably happy with the Magnaclean, though. Quite well designed and
easy to clean out (it comes with isolating valves) and it is a convenient
point to add inhibitor, slightly more convenient than via radiators.

On Sat, 31 Oct 2009 12:36:50 +0000, newshound wrote:

time I tried a chemical clean on the removed heat exchanger using formic
acid (kettle descaler) plus flushing. Not the ideal chemical approach,
hydrochloric acid (brick acid) would be better but this can be bad for
stainless steel heat exchangers.

I tried fairly concentrated HCl on the PHE and on a sample of the gritty
magnetic crud blocking one up and it had no effect on them.


--
John Stumbles -- http://yaph.co.uk

I've got nothing against racists - I just wouldn't want my daughter to marry one