Honeywell ST7100 Randomness

Dec 13, 2015 15 Replies

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polygonum 10 years ago

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?

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Graham. 10 years ago

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?

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ARW 10 years ago

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

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Davey 10 years ago

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.

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Davey 10 years ago

I also found this:

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polygonum 10 years ago

Absolutely true!

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ARW 10 years ago

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

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polygonum 10 years ago

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.

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Graham. 10 years ago

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

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polygonum 10 years ago

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

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Davey 10 years ago

Phew. I was wondering where that came from!

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Chris French 10 years ago

In message , polygonum writes

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

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polygonum 10 years ago

Yes - had to reset everything. :-)

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ARW 10 years ago

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.

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Johnny B Good 10 years ago

You weren't the only one. :-)

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polygonum 10 years ago

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

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