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Ask Andrew Smith Your Own Question
Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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I am an Electrician and was asked to look at a customers

Customer Question

HI, I am an Electrician and was asked to look at a customers boiler who thought the thermostat controlling the Hot water was faulty Hot Water too hot. However on looking at the Boiler a very Old Vulcan Autostat. the system appears to have two separately circuits, One heating and one hot water. There is no Cylinder thermostat and only one two port valve for the Hot water. Can you confirm if the Hot water is controlled separately via an internal controller?Thanks Steve
JA: How long has this been going on? And how severe is the problem?
Customer: Only called in today the lady is into well into her early eighties so getting information is slow, but I believe for a week / ten days. the hot water is just to hot for me. Forgot to say the boiler control stat works and is currently turned down to 120F
JA: Do you plan on doing the work yourself?
Customer: Not if I can find a good local boiler engineer to take it on, Just wanted to know if the hot water controll was via an internal sensor stat and not via a typical 's' or Y plan.
JA: Anything else we should know to help you best?
Customer: Can you confirm parts for these boilers are no longer available
Submitted: 10 months ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 10 months ago.

Its strange to have a valve on the hot water and not heating, perhaps it is under the floor?

The valve will be controlled by the programmer, but you could interrupt the feed with a cylinder stat to control the temperature.

Customer: replied 10 months ago.
Sorry my mistake have just re-read my post (typo error), the valve is on the heating system not the hot water. I was expecting to find a valve on the hot water controlled via a cylinder stat.
I just needed to know if this old boiler had a separate circuit for hot water controlled by an internal thermostat or sensor. It would appear to have two circuits coming out of the back of the boiler (as far as I can see) one heating the other Hot Water.
Expert:  Andrew Smith replied 10 months ago.

4 pipes out of the boiler could be gravity hot water.

If this is the case then the hot water is controlled by the boiler stat and the heating is controlled by the pump

Customer: replied 10 months ago.
Thanks Andrew, your reply got my old grey cells working again, and I can remember coming across a few of these system over the years. I seem to remember and I have just confirmed this (Google can be helpful) that they sometimes had a mechanical type valve / sensor on the flow or return as a rudimentary temperature controller for the hotwater.
If I get chance I will call in and have another look.
Thanks again
Expert:  Andrew Smith replied 10 months ago.

no problem, let me know if you get stuck