Hope someone can offer me some advice on my problems with my new boiler.
After 13 years of good service, my Vaillant Combi boiler broke down.

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!
The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

The Vaillant guy came round today and after 1 minute of oooh-ing and
ahh-ing, said that I need to power flush the whole system and only then
will they replace the heat transfer unit inside the boiler.

I've just now got off the phone to my plumber and was shocked to find
that a Power Flush would cost me up to £800!!!

Its far to much money for me to spend, but if its 100% the route of the
problem I guess I'll spend the money. My main concern is that the
reasons I was given for a power flush does not make sense. My old boiler
heated up the water fine. If there is grime in the system I would expect
the new boiler to work less and less efficiently over a period of time,
say six months. The new boiler failed to send hot enough water up to my
shower from the moment it was installed.

I wish I had brought these questions up when the Vaillant guy was here,
but a 'power flush' didn't sound like a big job. I shouldn't have been
so naive, ANY job is a big job for a @?%$£"^ plumber.

Any advice? Is a power flush my only option?

Thanks

OVS wrote:

Recently (about 2 weeks ago), I replaced the boiler with a new
Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler.

Manufacturers require all replacement boilers are fitted to a system
which has been powerflushed or chemically cleansed. If that job is not
done, then its easy for them to void the warranty in the same way that
the benchmark book must be signed off by a Corgi who did the
installation/commissioning.

I think that will find that unless you have a powerflushing or cleaning
done, then Vaillant can claim to void the warranty. I don't know if
they would allow a DIY powerflush/clean acceptable in this regard.
Martyn

OVS wrote:

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!
The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

Obvious question, did your previous model throttle the mains water flow
through it and have you done the same for this one?
This model will probably allow a higher flow rate than your previous
boiler, which is going to equate to a lower temperature rise...

Our 828 easily heats the DHW to 70C, but we have the flow rate throttled
back to around 9 lpm. (due to a problem we have with flow noise in the
mains water pipes).

Lee
--
Email address is valid, but is unlikely to be read.

OVS wrote:

Hope someone can offer me some advice on my problems with my new boiler.
After 13 years of good service, my Vaillant Combi boiler broke down.

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!
The ground level water reaches high temperatures fine. By the way,

Don't understand that bit about the ground water temperature...

Do you mean the hot water temperature from taps other than the shower is OK?

what's the average expected temperature for hot water using a modern
boiler?

Typically they have a thermostat that will limit the maximum temperature
to between 40 and 65 degrees depending on where you set it.

The Vaillant guy came round today and after 1 minute of oooh-ing and
ahh-ing, said that I need to power flush the whole system and only then
will they replace the heat transfer unit inside the boiler.

There may well be an argument for flushing the system. However that is
unlikly to be the cause of your current problem.

problem I guess I'll spend the money. My main concern is that the
reasons I was given for a power flush does not make sense. My old boiler

Well it won't make sense, when using a combi for HW it will be
circulating the water heated by the burner through an internal loop, not
your heating system.

heated up the water fine. If there is grime in the system I would expect
the new boiler to work less and less efficiently over a period of time,
say six months. The new boiler failed to send hot enough water up to my
shower from the moment it was installed.

"grime" in the system may reduce efficency of the heating, and may cause
premature wear and corrosian in the boiler. It should not make any
difference to HW performance.

Any advice? Is a power flush my only option?

Obvious thing to check, is there a water temperature selection on the
boiler? If so is it at a maximum setting or can you turn it up?

What is the temperature from the nearest hot tap to the boiler like?
Much hotter than the shower? (if yes then that would point to an issue
with the shower and not the boiler)

Is your shower a thermostatic or pressure balanced one?

Is your shower one of those that required lots of water (i.e. big
drencher head or extra body jets etc)? What happens if you turn the flow
rate down a bit in the shower, does it get hotter then?

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
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\================================================= ================/

OVS wrote:

The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

Ignore my other post, was looking at the flow temp on the boiler Doh!...

Looking at the specs, the 828 is setup to a temperature rise of 42C @ a
flow rate of 9.5 lpm.
If the incoming mains cold is say 10C, then that's only going to give
you a DHW of 52C and that's if you throttle the flow the 9.5 lpm...

Lee

--
Email address is valid, but is unlikely to be read.

"Lee" wrote in message
...
OVS wrote:

The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

Ignore my other post, was looking at the flow temp on the boiler Doh!...

Looking at the specs, the 828 is setup to a temperature rise of 42C @ a
flow rate of 9.5 lpm.
If the incoming mains cold is say 10C, then that's only going to give
you a DHW of 52C and that's if you throttle the flow the 9.5 lpm...

I have an 828 and with the temperature control turned right down it gave hot
water at 49C from ground water at 16C: that's a rise of 33C, admittedly at
an unknown flowrate ( I cracked open a cloakroom basin tap to full
throttle ). Now, I found it very difficult to keep my hand in water at 49C,
so 52C would be unbearable. Also, the 828, as I implied, can deliver HW at
different temperature rises, and I've seen 11 ltrs/min at a delta T of 35C
quoted. I have also meaured the maximum temperature of HW with the
temperature knob set to max. (fully CW), and that was 64C.

To summarise, I think that with a small basin tap cracked fully open, the
maximum temperature you can get from an 828 is ~64C, and the minimum would
be about the groundwater temperature plus 33C. This may help in determining
if you have a real problem.

The engineer chappy seems to be suggesting that your HW heat exchanger is
not working properly beacause it is gummed up with sludge from your CH
system. I suppose that is possible, since the boiler loop has the CH fluid
as its working fluid. I can't comment on this £800 for a power flush ( seems
ridiculous though ), but I'd want to know if that was the problem first, so
you need to find out, somehow, whether your boiler loop/DHW heatexchanger
( the sardine tin ) is gummed up with clag. That would be my approach.

Andy.

Andy.

Recently (about 2 weeks ago), I replaced the boiler with a new
Vaillant Combi (828 turboMax). Since using the new boiler, the shower
water doesn't reach the hot temperatures it once did with the old
boiler. Its maximum temperature is hot side of tepid, but not
searingly hot the way I like it!
The ground level water reaches high temperatures fine. By the way,


Don't understand that bit about the ground water temperature...

Do you mean the hot water temperature from taps other than the shower is
OK?


Sorry, by ground I meant the downstairs tap, nearest to the boiler and
yes its all fine other than the water from the shower which is situated
one floor up.




Obvious thing to check, is there a water temperature selection on the
boiler? If so is it at a maximum setting or can you turn it up?

There is a water Temperature selector on the boiler, and its already
turned all the way to maximmum.


What is the temperature from the nearest hot tap to the boiler like?
Much hotter than the shower? (if yes then that would point to an issue
with the shower and not the boiler)

Is your shower a thermostatic or pressure balanced one?


Its just the shower which is having this problem. Its a very basic
shower unit. Only two knobs, amount of water and hot/cold mixture.
You're right, the problem does point to the shower, but it worked fine
with the previous boiler. With the previuos boiler I would set the
mixture to 75%hot and 25% cold, now 100% hot water doesn't feel hot enough.

Is your shower one of those that required lots of water (i.e. big
drencher head or extra body jets etc)? What happens if you turn the flow
rate down a bit in the shower, does it get hotter then?


I've just tried this now, it doesn't make a noticable difference in temp
if i decrease the flow.

I've decided to leave it as it is for now, the temperatures bearable for
now and the central heating and everything else works fine.

I'm stumped, although saying that, it doesn't take much to stump me when
it comes to anything to do with electrical stuff or plumbing.


Thanks for the reply John, and also to the others who have replied.

On Thu, 13 Jan 2005 11:56:16 +0000, OVS wrote:

Hope someone can offer me some advice on my problems with my new boiler.
After 13 years of good service, my Vaillant Combi boiler broke down.

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!
The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

The Vaillant guy came round today and after 1 minute of oooh-ing and
ahh-ing, said that I need to power flush the whole system and only then
will they replace the heat transfer unit inside the boiler.

I've just now got off the phone to my plumber and was shocked to find
that a Power Flush would cost me up to £800!!!

Its far to much money for me to spend, but if its 100% the route of the
problem I guess I'll spend the money. My main concern is that the
reasons I was given for a power flush does not make sense. My old boiler
heated up the water fine. If there is grime in the system I would expect
the new boiler to work less and less efficiently over a period of time,
say six months. The new boiler failed to send hot enough water up to my
shower from the moment it was installed.

I wish I had brought these questions up when the Vaillant guy was here,
but a 'power flush' didn't sound like a big job. I shouldn't have been
so naive, ANY job is a big job for a @?%$£"^ plumber.


Others have said good things.
The primary side should have been cleaned out before fitting anyway.
Even BG only want about £500 for power cleaning so £800 is way way over
the odds.

Since it is new we can rule out 2ndary scaling (and you might be
a soft water area anyhow).

To get hotter HW from a T/max 828 you will need to do either or both of
two things.

Firstly the there is a separate _MAXIMUM_ HW temperature control the top
end of this is likely around the equivalent of 65-70C which is rather more
than 'searing' more like 'flesh consuming'. However since the temperature
of the ground floor outlets is OK this does not need moving. I.e. the
boiler's maximum is not too low (otherwise you would not get hot enough HW
on the ground floor).

Secondly you may find that you need to restrict the flow of water through
the boiler in order to get hotter HW. This you can do on any tap by simply
opening it less. However it may well be more convenient to simply restrict
the water flow in general: for this there is restrictor it is underneath
the boiler in the same fitting as the cold water inlet valve. The
restrictor has a hex (about 8mm AF?) headed spindle, these are generally
set to full open 'out of the box'.

If the 'plumber' who fitted the boiler did not sign the book saying what
was used to flush the system then I would get him back to do so.
[On pain of a complaint to CORGI if needed. Those of us who do thing
properly are getting ****ed off by the slap-dash who charge the same for
doing less.]

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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

"Ed Sirett" wrote in message
news
On Thu, 13 Jan 2005 11:56:16 +0000, OVS wrote:

Hope someone can offer me some advice on my problems with my new boiler.
After 13 years of good service, my Vaillant Combi boiler broke down.

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!
The ground level water reaches high temperatures fine. By the way,
what's the average expected temperature for hot water using a modern
boiler?

The Vaillant guy came round today and after 1 minute of oooh-ing and
ahh-ing, said that I need to power flush the whole system and only then
will they replace the heat transfer unit inside the boiler.

I've just now got off the phone to my plumber and was shocked to find
that a Power Flush would cost me up to £800!!!

Its far to much money for me to spend, but if its 100% the route of the
problem I guess I'll spend the money. My main concern is that the
reasons I was given for a power flush does not make sense. My old boiler
heated up the water fine. If there is grime in the system I would expect
the new boiler to work less and less efficiently over a period of time,
say six months. The new boiler failed to send hot enough water up to my
shower from the moment it was installed.

I wish I had brought these questions up when the Vaillant guy was here,
but a 'power flush' didn't sound like a big job. I shouldn't have been
so naive, ANY job is a big job for a @?%$£"^ plumber.


Others have said good things.
The primary side should have been cleaned out before fitting anyway.

When fitting a new boiler on an old system a strainer must always be fitted
on the return to the boiler to catch any debris or sludge.

On Thu, 13 Jan 2005 16:31:58 -0000, "IMM" wrote:

When fitting a new boiler on an old system a strainer must always be fitted
on the return to the boiler to catch any debris or sludge.

A suitable part is?

M.

"Markus Splenius" wrote in message
...
On Thu, 13 Jan 2005 16:31:58 -0000, "IMM" wrote:

When fitting a new boiler on an old system a strainer must always be
fitted
on the return to the boiler to catch any debris or sludge.

A suitable part is?

A 22mm or 28mm strainer, available from http://www.bes.ltd.uk, or any
plumbers merchant.

Look original poster, you need to establish the flow rate from a tap in the bathroom is as per the spec of the boiler. You won't have a weir guage so you'll have to get a thermometer, run tap and adjust until the temp is the cold tap temp plus the rise used by vaillant. measure the quantity of water passed in 20 seconds and multiply by three.

If this test shows that the boiler is functioning correctly you should take the
the hot connection off the shower and see if there is a strainer. Is it blocked? Or if there isn't one to what extent you can clean the shower. Is there a flow restrictor in the hot inlet? Try removing it.

You can buy a small powerflush machine (Rothenberger) for £300 plus vat. Buy your own rather than spend what you've been asked. I charge £350, but my area isn't the most expensive in the country.

Anyhow it is very likely a bit of flux or something has got itself up there into the shower.

Paul

Recently (about 2 weeks ago), I replaced the boiler with a new Vaillant
Combi (828 turboMax). Since using the new boiler, the shower water
doesn't reach the hot temperatures it once did with the old boiler. Its
maximum temperature is hot side of tepid, but not searingly hot the way
I like it!

The flow rate may not be as high on this boiler so if you have a flow
restricter in the cold supply to the shower, you may need to reduce the
flow a little.

Just a guess though, i`m crap at DIY :-}

--
Please add "[newsgroup]" in the subject of any personal replies via email
--- My new email address has "ngspamtrap" & @btinternet.com in it ;-) ---

On Thu, 13 Jan 2005 17:12:30 +0000, IMM wrote:


"Markus Splenius" wrote in message
...
On Thu, 13 Jan 2005 16:31:58 -0000, "IMM" wrote:

When fitting a new boiler on an old system a strainer must always be
fitted
on the return to the boiler to catch any debris or sludge.

A suitable part is?

A 22mm or 28mm strainer, available from http://www.bes.ltd.uk, or any
plumbers merchant.

I have no problem with fitting one, however Vaillant _do_ specifiy two
flush outs and _don't_ specify the use of a return pipe strainer.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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

"Ed Sirett" wrote in message
news
On Thu, 13 Jan 2005 17:12:30 +0000, IMM wrote:


"Markus Splenius" wrote in message
...
On Thu, 13 Jan 2005 16:31:58 -0000, "IMM" wrote:

When fitting a new boiler on an old system a strainer must always be
fitted
on the return to the boiler to catch any debris or sludge.

A suitable part is?

A 22mm or 28mm strainer, available from http://www.bes.ltd.uk, or any
plumbers merchant.

I have no problem with fitting one, however Vaillant _do_ specifiy two
flush outs and _don't_ specify the use of a return pipe strainer.

Some makers do. It is common sense to fit one in an old system as it
catches any crap before it get into the boiler. If using 22mm pipe best to
use a 28mm strainer and have full bore isolation valves either side, for
ease of cleaning with a drain down. In fact they should be built inside
boilers. Alpha boilers have a cyclone system which directs crap into a
trap.