Hi,

I have just had a new worcester 25si greenstar boiler fitted and I am
keen to change my old electric shower for a mira excel. I have read
through the instructions for fitting he mira excel and there was a few
questions I have and wondered if someone could advise me.

The following is from the fitting instructions:

iInstantaneous gas-heated showers (e.g. combination boilers)
The shower control MUST be installed with a multipoint gas water heater
or combination
boiler of a fully modulating design (i.e. where the water draw-off rate
indirectly
controls the gas flow rate to the burner).
A drop tight pressure reducing valve MUST be fitted if the supply
pressures exceed 5
bar maintained.
An expansion vessel MUST be fitted (and regularly maintained) as shown
in the
diagram below to ensure that excess pressures do not damage the
product. This may
already be fitted within the boiler (check with the manufacturer) and
is in addition to
the normally larger central heating expansion vessel.
The hot supply temperature MUST be at least 12 °C hotter than the
required blend
temperature for optimum performance./i

My questions are is the 25si fitted with an appropriate expansion
vessel? The instructions say it has one but I'm not sure if this is
purely for the central heating.

Does the 25si's supply pressure exceed 5 bar and if so how easy is a
drop tight pressure reducing valve to fit?

The last question is is this a job for a diy plumber or would it be
better for a plumber to do it. The main reason I want to do it is I
enjoy diy and get a lot of satisfaction from it, plus I have to tile
around the old shower and live without a shower for a few days and dont
want to have to rely on a plumber to turn up!

Thanks.

In message .com, dp
writes
Hi,

I have just had a new worcester 25si greenstar boiler fitted and I am
keen to change my old electric shower for a mira excel. I have read
through the instructions for fitting he mira excel and there was a few
questions I have and wondered if someone could advise me.


snip

My questions are is the 25si fitted with an appropriate expansion
vessel? The instructions say it has one but I'm not sure if this is
purely for the central heating.


Pass, ring Bosch? maybe. I fitted an excel a few years ago in my old
house don't remember if it was a requirement then or if my boiler had
one.
Does the 25si's supply pressure exceed 5 bar

That depends on your mains pressure. We had to high a pressure in our
mains (in the summer) for the shower (symptoms are whistling from the
shower valve) that mostly seemed to be an issue with the cold supply

and if so how easy is a
drop tight pressure reducing valve to fit?

Easy enough, it just plumbs into the supply pipe to the shower with
compression connections.

The last question is is this a job for a diy plumber or would it be
better for a plumber to do it.

I installed our Excel with no problems - plastic pipe (Hep2O made the
rujn down the wall and under the shower tray easy.

--
Chris French