Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell end.

A quick check on the Honeywell site says that bypasses are needed. Is there
chapter and verse anywhere else to say that they are needed?

Adam

"ARWadworth" wrote in message
om...
Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell end.

A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

The boiler manual will state if it needs one.

"dennis@home" wrote in message
...


"ARWadworth" wrote in message
om...
Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell end.

A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

The boiler manual will state if it needs one.

No manual!

Adam

"ARWadworth" wrote in message
m...

"dennis@home" wrote in message
...


"ARWadworth" wrote in message
om...
Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell
end.

A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

The boiler manual will state if it needs one.

No manual!

What model?

Adam

In article , ARWadworth
writes
Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

Not necessarily automatic, but yes, some sort of bypass is required and
automatic is better. (in t'old days it was a gate valve across the flow
and return, a bit from the boiler, set to give just the right amount of
flow to allow some bypass flow when the zone valves are shut but without
short circuiting the heating loop)

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell end.

The heat needs to go somewhere, the boiler has some thermal mass so even
when it stops firing it needs flow to cool it down or it will (as you've
found) overheat, it may make boiling noises or trip the overheat or it
may just stew a bit and hate you for stressing it. S-Plan has no flow
when both paths are off so you need a bypass to allow flow, simple as
that.

No amount of rewiring can stop a boiler overheating if there is no flow
to take the residual heat away.

Unless the boiler has an internal bypass you need an external one.

A quick check on the Honeywell site says that bypasses are needed. Is there
chapter and verse anywhere else to say that they are needed?

No refs I'm afraid, just common sense. Would a print of the Honeywell
spiel help? Would they/could they read it?
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

In an earlier contribution to this discussion,
ARWadworth wrote:

Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass,
the valves close and the pump over run is then causing the boiler
over heat switch to kick in. The plumber, who is a friend of the
customer, keeps telling them that the wiring is wrong. I think the
plumber is a bell end.
A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

Adam

S-Plan systems don't *all* need a by-pass - but most do. It depends on the
boiler. If the boiler controls the pump and keeps it running (usually called
pump over-run) for a bit to remove the residual heat after all demands have
been satisfied (and the zone valves have closed) the water needs somewhere
to go. With the zone valves closed, it can't go via the normal routes so
there needs to be a by-pass. The best sort are automatic (spring loaded) and
only open when the pump pressure is higher than normal due to the HW and CH
circuits being closed.

Examine the way the pump is wired and see whether it is controlled by the
boiler. If it is, the boiler will have specific terminals for the pump
connections in addition to live, neutral and earth. It will also have a
permanent live as well as a switched live so that it can power the pump when
all demands are off.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
ARWadworth wrote:

Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass,
the valves close and the pump over run is then causing the boiler
over heat switch to kick in. The plumber, who is a friend of the
customer, keeps telling them that the wiring is wrong. I think the
plumber is a bell end.
A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

Adam

S-Plan systems don't *all* need a by-pass - but most do. It depends on the
boiler. If the boiler controls the pump and keeps it running (usually
called pump over-run) for a bit to remove the residual heat after all
demands have been satisfied (and the zone valves have closed) the water
needs somewhere to go. With the zone valves closed, it can't go via the
normal routes so there needs to be a by-pass. The best sort are automatic
(spring loaded) and only open when the pump pressure is higher than normal
due to the HW and CH circuits being closed.

Examine the way the pump is wired and see whether it is controlled by the
boiler. If it is, the boiler will have specific terminals for the pump
connections in addition to live, neutral and earth. It will also have a
permanent live as well as a switched live so that it can power the pump
when all demands are off.

There is a pump over-run (twas in my original message :-)). But you have
answered my question, "not" all S Plans need a bypass.

I wired the system up 5 years ago and it has worked fine until last week. I
called and had another look at the job today.

The customer eventually told me that the plumber replaced their cylinder
with a second hand one last week and that is when the problems started. So
job sorted, the plumber has removed the bypass IMHO.

Adam

"ARWadworth" wrote in message
om...

I wired the system up 5 years ago and it has worked fine until last week.
I called and had another look at the job today.


The customer has probably been told by the plumber to clear off.
Do the same.

The customer eventually told me that the plumber replaced their cylinder
with a second hand one last week and that is when the problems started. So
job sorted, the plumber has removed the bypass IMHO.

Adam

On Thu, 02 Oct 2008 17:44:02 +0000, ARWadworth wrote:

Apologies up front, this is not a DIY question but a work related one

Do all S Plans needs an automatic bypass? I assume that they do.

I am getting grief off a customer who has an S plan with no bypass, the
valves close and the pump over run is then causing the boiler over heat
switch to kick in. The plumber, who is a friend of the customer, keeps
telling them that the wiring is wrong. I think the plumber is a bell
end.

A quick check on the Honeywell site says that bypasses are needed. Is
there chapter and verse anywhere else to say that they are needed?

Adam

Yes, unless it's already in the boiler.


--
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