Hi Guys

A number of posters have given good reports of Worcester-Bosch boilers so I
am considering one for my heating upgrade.

Can someone who knows help me with some clarification please?

On the web site, the 29HE is stated as suitable for a small to medium house,
whereas the 28HE states medium to large. How can this be when the 29HE has
the slightly higher output?

The larger models state that a modulating pump is included in the "system"
boiler options. Is this the same as a Grundfos Alpha type model, and would
these be compatible with the 29HE?

I have heard that some system boilers have an inaccessible expansion vessel
which means major dismantling in the event of problems with diaphragm etc.
Is this the case with the 28HE?


To be honest, I am undecided whether to go:

a) 29HE with external pump and leave system as is (with expansion tank in
loft)
b) 29HE with external pump but convert to sealed system by fitting expansion
vessel in airing cupboard
c) 28HE and convert to sealed system

My house is 1970s construction with mostly new rads that I have replaced
myself.

Any thoughts/clarification appreciated

Phil

"TheScullster" wrote in message
...
Hi Guys

A number of posters have given good reports of Worcester-Bosch boilers so
I
am considering one for my heating upgrade.

Can someone who knows help me with some clarification please?

On the web site, the 29HE is stated as suitable for a small to medium
house,
whereas the 28HE states medium to large. How can this be when the 29HE
has
the slightly higher output?

They are about the same. The marketing people got it wrong.

The larger models state that a modulating
pump is included in the "system"
boiler options. Is this the same as a
Grundfos Alpha type model, and would
these be compatible with the 29HE?

The pump is modulated by the boiler controls, not an Alpha which has its own
controls.

I have heard that some system boilers
have an inaccessible expansion vessel
which means major dismantling in the
event of problems with diaphragm etc.
Is this the case with the 28HE?

No. it is on the side and slots out. Some other makes have them at the back
of the heat exchanger between the wall and the exchanger. These are
difficult to replace. Most tend to cap the old vessel off and fit an
external vessel on the heating return.

Go to the B-W web site and download the service manual for the boilers. It
clearly shows the vessel location.

To be honest, I am undecided whether to go:

a) 29HE with external pump and leave system as is (with expansion tank in
loft)

This is the easiest. Just a straight exchange.

b) 29HE with external pump but convert
to sealed system by fitting expansion

vessel in airing cupboard
c) 28HE and convert to sealed system

This is best as all is in one box.

My house is 1970s construction with mostly new rads that I have replaced
myself.

Any thoughts/clarification appreciated

With these models the electrical power must go through the boiler first. Yo
u may have a bit of requiring of your controls.

"TheScullster" wrote in message
...
Hi Guys

A number of posters have given good reports of Worcester-Bosch boilers so
I am considering one for my heating upgrade.

Can someone who knows help me with some clarification please?

On the web site, the 29HE is stated as suitable for a small to medium
house, whereas the 28HE states medium to large. How can this be when the
29HE has the slightly higher output?

From what I can tell the 29HE is a standard boiler while the 28HE is a
system boiler, which you've kind of answered below anyway.


The larger models state that a modulating pump is included in the "system"
boiler options. Is this the same as a Grundfos Alpha type model, and
would these be compatible with the 29HE?

I have heard that some system boilers have an inaccessible expansion
vessel which means major dismantling in the event of problems with
diaphragm etc. Is this the case with the 28HE?


To be honest, I am undecided whether to go:

a) 29HE with external pump and leave system as is (with expansion tank in
loft)
b) 29HE with external pump but convert to sealed system by fitting
expansion vessel in airing cupboard
c) 28HE and convert to sealed system

My house is 1970s construction with mostly new rads that I have replaced
myself.

Any thoughts/clarification appreciated

Phil

c) 28HE and convert to sealed system

Do this. Gravity fed systems are a real PITA. Sealed is the eay to go.

Christian.

In article ,
Christian McArdle wrote:
c) 28HE and convert to sealed system

Do this. Gravity fed systems are a real PITA. Sealed is the eay to go.

Explain? There seem to be a lot of problems mentioned here with them. Of
course if you don't have room for a header tank, fine.

--
*Organized Crime Is Alive And Well; It's Called Auto Insurance.

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

Explain? There seem to be a lot of problems mentioned here with them. Of
course if you don't have room for a header tank, fine.

They're nothing compared to problems with tanked systems.

Some problems with gravity fed, I'm sure there are more.

1. Hard to refill. Air locks abound.
2. Unlimited loss of water in the event of a leak.
3. Failure to detect leaks for long periods due to replenishment.
4. Pumping over, introduces new water and air, leading to corrosion.
5. "Debugging" circulation issues very difficult and can prevent high pump
speeds.
6. Incompatible with most modern boilers.
7. Requires pipework in loft, which may freeze and leak.
8. Venting arrangements may be unreliable due to long or convoluted vent
pipework runs.

Christian.

In article ,
Christian McArdle wrote:
Explain? There seem to be a lot of problems mentioned here with them. Of
course if you don't have room for a header tank, fine.

They're nothing compared to problems with tanked systems.

I've not had any problems in many years with mine. Apart from air locking
on filling, but that's easily got round.

Some problems with gravity fed, I'm sure there are more.

1. Hard to refill. Air locks abound.

I'd agree that one, but how often do you do this?

2. Unlimited loss of water in the
event of a leak.

Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

3. Failure to detect leaks for long periods due to
replenishment.

But when a pressurised systems loses pressure, most just seem to top them
up, so the same thing?

4. Pumping over, introduces new water and air, leading to
corrosion.

Badly designed in the first place, then.

5. "Debugging" circulation issues very difficult and can
prevent high pump speeds.

I'd rather not move the water around too fast due to noise.

6. Incompatible with most modern boilers.

Why is that?

7. Requires pipework in loft, which may freeze and leak.

The same applies to a storage water system, and I'm certainly not giving
that up.

8. Venting arrangements may be unreliable due to long or convoluted vent
pipework runs.

Again, down to design and installation.

Thanks for the info, though. But it still seems to me just more thing to
go wrong, for no obvious benefits other than ease of installation.

--
*Drugs may lead to nowhere, but at least it's the scenic route *

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

2. Unlimited loss of water in the
event of a leak.

Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

This is only safe if the boiler has a manual reset overheat lockout (i.e. is
suited to sealed pressurised operation). The safety "mechanism", if you can
call it that, for a boiler without an overheat lockout is to have an
uninterrupted vent to get rid of the steam, and an uninterrupted independent
path for quenching water, so it can boil away merrily until someone bothers
to turn it off. With a stopcock on the feed, it will run out of water and
possibly burn the house down.

But when a pressurised systems loses pressure, most just seem to top them
up, so the same thing?

Well, the clues are there, you can choose to ignore them.

8. Venting arrangements may be unreliable due to long or convoluted vent
pipework runs.

Again, down to design and installation.

But can be difficult or impossible to achieve, with the tank in the loft and
the boiler in a kitchen, in the rear "extension" bit.

Christian.

In article ,
Christian McArdle wrote:
This is only safe if the boiler has a manual reset overheat lockout
(i.e. is suited to sealed pressurised operation). The safety
"mechanism", if you can call it that, for a boiler without an overheat
lockout is to have an uninterrupted vent to get rid of the steam, and an
uninterrupted independent path for quenching water, so it can boil away
merrily until someone bothers to turn it off. With a stopcock on the
feed, it will run out of water and possibly burn the house down.

It was common practice years ago to have no feed at all to the header
tank. Servowarm, for one. And of course the first sign of the level being
low is the upper floor rads not working.

Boilers in those days didn't have overheat lockouts - but I can't remember
it being common for them to start fires. ;-)

--
*Growing old is inevitable, growing up is optional *

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

"Dave Plowman (News)" wrote in message
...
In article ,
Christian McArdle wrote:
Explain? There seem to be a lot of problems mentioned here with them.
Of
course if you don't have room for a header tank, fine.

They're nothing compared to problems with tanked systems.

I've not had any problems in many years with mine. Apart from air locking
on filling, but that's easily got round.

Some problems with gravity fed, I'm sure there are more.

1. Hard to refill. Air locks abound.

I'd agree that one, but how often do you do this?

2. Unlimited loss of water in the
event of a leak.

Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

Absolute madness.

"Christian McArdle" wrote in message
. net...
2. Unlimited loss of water in the
event of a leak.

Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

This is only safe if the boiler has a manual reset overheat lockout (i.e.
is
suited to sealed pressurised operation). The safety "mechanism", if you
can
call it that, for a boiler without an overheat lockout is to have an
uninterrupted vent to get rid of the steam, and an uninterrupted
independent
path for quenching water, so it can boil away merrily until someone
bothers
to turn it off. With a stopcock on the feed, it will run out of water and
possibly burn the house down.

There are one pipe feed/expansion systems using a header tank. In this case
the boiler must have extra protection, such as dry fire protection. They are
pig to get the air out if no adequate auto air vents are installed.

In article ws.net,
Doctor Evil wrote:
Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

Absolute madness.

Stick to things you know even less about.

--
*Women like silent men; they think they're listening.

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

On Tue, 28 Jun 2005 08:56:52 +0100, TheScullster wrote:

Hi Guys

A number of posters have given good reports of Worcester-Bosch boilers so I
am considering one for my heating upgrade.

Can someone who knows help me with some clarification please?

On the web site, the 29HE is stated as suitable for a small to medium house,
whereas the 28HE states medium to large. How can this be when the 29HE has
the slightly higher output?

The larger models state that a modulating pump is included in the "system"
boiler options. Is this the same as a Grundfos Alpha type model, and would
these be compatible with the 29HE?

I have heard that some system boilers have an inaccessible expansion vessel
which means major dismantling in the event of problems with diaphragm etc.
Is this the case with the 28HE?


To be honest, I am undecided whether to go:

a) 29HE with external pump and leave system as is (with expansion tank in
loft)
b) 29HE with external pump but convert to sealed system by fitting expansion
vessel in airing cupboard
c) 28HE and convert to sealed system

My house is 1970s construction with mostly new rads that I have replaced
myself.

Any thoughts/clarification appreciated

Phil

How long is a piece of string. small/medium/big house ?

Unless your house is really large I suspect that all these models are
bigger than you really need.

Read the SealedCH FAQ for back ground reading.

The system boiler contains the pump and this is good because the boiler
control the pump speed to match the gas rate.

I'd definately go for c but check if you really need the boiler to be that
size.


--
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

"Dave Plowman (News)" wrote in message
...
In article ws.net,
Doctor Evil wrote:
Put a stopcock in the cold water feed if it bothers you. Then you're
limited to the contents of the tank.

Absolute madness.

Stick to things you know even less about.

You are just plain dangerous.

In article , Dave Plowman (News)
wrote:
It was common practice years ago to have no feed at all to the
header tank. Servowarm, for one.

An ex-plumber I worked with reckoned that this was because Servowarm
installers were not to be trusted to cut into an existing main - they
could do new copper and compression joints but not necessarily
anything else.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

In article ,
Tony Bryer wrote:
It was common practice years ago to have no feed at all to the
header tank. Servowarm, for one.

An ex-plumber I worked with reckoned that this was because Servowarm
installers were not to be trusted to cut into an existing main - they
could do new copper and compression joints but not necessarily
anything else.

Heh heh. My theory was it simply to save money.

--
*I'm not as think as you drunk I am.

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

Or it could be to encourage plumbers to top up the tank by "internal"
means
so that they could get their 15 minutes of fame via a "dodgy builder"
television
programme?
Mungo

P.S. Now a proud owner of a 40Kw Worcester Bosch condensing boiler. I
know
it's the summer but on the cold mornings when the boiler kicks in it is
amazing how
fast our radiators warm up now compared to the old 24Kw boiler.

Thanks Ed

This thread has lost its way somewhat, so I will start new thread with
subject Help with Boiler Selection

Phil

On Wed, 29 Jun 2005 10:55:09 +0100, Dave Plowman (News) wrote:

In article ,
Tony Bryer wrote:
It was common practice years ago to have no feed at all to the
header tank. Servowarm, for one.

An ex-plumber I worked with reckoned that this was because Servowarm
installers were not to be trusted to cut into an existing main - they
could do new copper and compression joints but not necessarily
anything else.

Heh heh. My theory was it simply to save money.

I'd go along with the save money idea. After all they would have to do the
gas connection so they'd have to up for that....
um.....
Yeah Right.

They used to justify the 'feature' by saying how that any flood would be
limited, a somewhat negative approach IMHO.

They also set fire to my neighbours house (ceiling void and blow lamps)
when they had there CH installed c. 1980.

--
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

In article .uk,
Ed Sirett wrote:
I'd go along with the save money idea. After all they would have to do
the gas connection so they'd have to up for that.... um..... Yeah Right.

They used to justify the 'feature' by saying how that any flood would be
limited, a somewhat negative approach IMHO.

Yup. If that was the only reason, you could fit a stopcock before the
ballvalve in the cold water feed and leave it closed until needed - to
save carrying buckets of water into the loft.

They also set fire to my neighbours house (ceiling void and blow lamps)
when they had there CH installed c. 1980.

Oh dear. They were the sort of Kwik-Fit of central heating, but like them
probably criticised more than they deserved. Wonder what happened to them?

--
*Even a blind pig stumbles across an acorn now and again *

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

On Wed, 29 Jun 2005 22:47:21 +0100, Dave Plowman (News) wrote:

In article .uk,
Ed Sirett wrote:
I'd go along with the save money idea. After all they would have to do
the gas connection so they'd have to up for that.... um..... Yeah Right.

They used to justify the 'feature' by saying how that any flood would be
limited, a somewhat negative approach IMHO.

Yup. If that was the only reason, you could fit a stopcock before the
ballvalve in the cold water feed and leave it closed until needed - to
save carrying buckets of water into the loft.

They also set fire to my neighbours house (ceiling void and blow lamps)
when they had there CH installed c. 1980.

Oh dear. They were the sort of Kwik-Fit of central heating, but like them
probably criticised more than they deserved. Wonder what happened to them?

They are still around. They upgraded my neighbours' heating. They added a
pipe and a valve to make topping up easier. A radio thermostat. A
motorized valve instead of the manual summer/winter diverter valve. They
also replaced the back boiler with the same which I was less keen to do
which is why they got the job.
In fact come to think of it their house (mine too for that matter) is one
of the few houses where a non-condensing exemption could be used.

--
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