Honeywell ST7100 Randomness

[polygonum]

We have an old boiler, and an old Honeywell ST7100 controller.

The other week, I replaced the batteries in the ST7100 - the old ones were well and truly flat. Since then, the heating has been switching on at 06:30 some days - but not all days.

Yes - have checked and re-checked the programming. The fact that it is right some days seems to confirm that aspect is OK. And the rest fo the programming is working as expected.

Any suggestions as to why it might come on half an hour early on seemingly random days?

[Graham.]

Do these things have some DIP switches or other means to pair the transmitter and receiver with a code? If the installer just left the setting at default, and your neighbour has one and does the same thing... ...can you see what I am getting at?

[ARW]

I can, but the ST7100 is not a RF controller!

[Davey]

Does it have options for different days? Keep a log, and see if it is always the same day(s) that it doesn't work.

I once rented a house in the USA which had a water softener, with a

6-day regeneration program. Most strange.

[Davey]

I also found this:

[polygonum]

Absolutely true!

[ARW]

And 6.30 am is THE defult setting for a ST7100 CH and a HW ON time

[polygonum]

As he has business interests in the UK, and is in effect an employer here, he might be breaking various UK laws regardless his actual physical location, nationality, etc.

[Graham.]

Give me a break. I can't be expected to be right all the time!

[polygonum]

Bizarre - my response above was to an entirely different thread. Goodness knows how it ended up here.

[Davey]

Phew. I was wondering where that came from!

[Chris French]

In message , polygonum writes

Have you reset it and redone the programming? (as opposed to just checking it's right)

[polygonum]

Yes - had to reset everything. :-)

[ARW]

What is the HW ON time set to?

If it is 6.30am than then you are looking at a sticking motorized valve. ie the HW comes on and also allows heats up the CH.

[Johnny B Good]

You weren't the only one. :-)

[polygonum]

All morning ON times are 07:00. I think!