I moved into my present house a few months ago. I have a Baxi WM 38/3RS gas
boiler which has an electronic timer connected but not a room thermostat.
When I moved in there weren't any thermostats at all in the house.

I have fitted 2 TRVs in the bathroom and living room but would like to have
a room thermostat fitted for controlling the operation of the boiler.
Unfortunately, there isn't any documentation to go with the boiler. I had an
electrician round the other day for a re-wiring quotation but he could not
work out how to connect a room thermostat to the boiler. I have checked the
Baxi website and Googled but cannot find any wiring details. Haven't
contacted Baxi yet. I noticed from Googling that the boiler may date back as
far as 1988.

Is it likely that a heating engineer would be familiar enough with these
boilers to fathom how to connect a room thermo or am I probably stuffed?
Otherwise, does anyone have a wiring diagram for this boiler?

AT
..

In an earlier contribution to this discussion,
AT wrote:

I moved into my present house a few months ago. I have a Baxi WM
38/3RS gas boiler which has an electronic timer connected but not a
room thermostat. When I moved in there weren't any thermostats at all
in the house.
I have fitted 2 TRVs in the bathroom and living room but would like
to have a room thermostat fitted for controlling the operation of the
boiler. Unfortunately, there isn't any documentation to go with the
boiler. I had an electrician round the other day for a re-wiring
quotation but he could not work out how to connect a room thermostat
to the boiler. I have checked the Baxi website and Googled but
cannot find any wiring details. Haven't contacted Baxi yet. I noticed
from Googling that the boiler may date back as far as 1988.

Is it likely that a heating engineer would be familiar enough with
these boilers to fathom how to connect a room thermo or am I probably
stuffed? Otherwise, does anyone have a wiring diagram for this boiler?

AT
.

A boiler wiring diagram is only part of the story - and you need to consider
the wiring of the overall system including pump, motorised valves (if any)
etc.

Presumably this boiler heats the water in a hot water cylinder, as well as
the radiators? Does the pump run when you're just heating the HW, or does it
only run for the CH? Are there any motorised valves in the system? If so,
how many and 2-port or 3-port?

Armed with answers to these questions, it won't be too difficult to work out
how to connect a room stat. Without this information, it's virtually
impossible.
--
Cheers,
Roger
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