New Boiler Installed, Thermostat is Flaking Out

[SpaceCowboy2071]

Hi,

I'm not at all a DIY guy, in fact I'm really naive when it comes to wiring and such. So, please forgive any silly questions.

We had a new boiler installed, a Vaillant ecoTec Plus 428 to be specific. Along with this the boiler controls replaced with Drayton unit (unit that turns the hot water and heating on separately).

Everything seems fine, except our existing thermostat is flaking out. It is a Drayton Digistat 3. I've tried reading the manual online, but it doesn't go into any elaborate detail as it's very basic.

Basically, the thermostat just went blank shortly after the whole installation and would not come on again. We had the company's electrician over to take a look (not the same guy, and not a boiler electrician, some drama going on with the builders, etc). He had a basic look and said as far as he could tell the wiring was good, and he did manage to get the thermostat to come on. However, it was still really flaky.

The battery indicator was flashing. So, after he left I got some batteries and replaced the old ones. The battery compartment is a bit loose, so after returning the unit to the wall it went blank again! After noticing the looseness of the compartment, I gave it a good shove and now we are back in business.

Anyway, after all of that it would seem to me that the unit actually runs off of the batteries. I thought they were just for back up. Is that correct? Are the hard line connections just there to control the boiler?

I'm just trying to educate myself on how things are suppose to work, so any advice is appreciated.

Thanks!

 

[D_Hailsham]

Do you mean the Digistat +3? If so, which version do you have - 22083 or 22087?

Or do you have the Digistat +3 RF (wireless)?

The 22083 and the RF version are both powered by batteries; the 22087 by 230v mains.

 

[SpaceCowboy2071]

No, it's the vanilla 3.

Here's a link the manual PDF:
Drayton Digistat 3 Manual

EDIT: I was googling around after posting this topic and saw some posts stating that some thermostats, regardless of their power source, require batteries to run. Perhaps that's the issue I'm having?

Thanks!

 

[Agile]

People often dont realise that some items like RF stats do need proper alkaline batteries and cheap carbon batts will not work properly.

Duracell are about the only make to be used in heating equipment.

Tony

 

[JohnD]

you might try lithium batts, which are more expensive but last a very long time

I think I paid about £7 for four Tesco Lithium AAs recently.

Maplins are very good for batts if you need a dozen or more. They have a ten-year shelf life.

 

[SpaceCowboy2071]

Thanks for the advice on which batteries might work best, however that's not my problem really.

I want to know that my thermostat is wired up correctly and is functioning correctly. So, do thermostats, such as the Drayton Digistat 3, require batteries to work?

I thought batteries were just for backup to keep the programs in memory, and that power for the thermostat is drawn from the mains. Therein lies my confusion.

Thanks again!

 

[JohnD]

it may also depend on how it is wired.

When I fitted a programmable stat in place of my old one, if CH was "off" at the boiler (it still has its own timer) then there was no power to the stat, and the batteries ran down (not the same stat as yours)

I fixed that by setting the boiler timer to "CH on 24 hours" and letting the programmable stat control the heating.

I see from the instructions for your one that when you are changing the batteries, the memory will be lost if you take more than a minute.

 

[D_Hailsham]

No, it's the vanilla 3.

Here's a link the manual PDF:
Drayton Digistat 3 Manual

If you look at the Spec (second page, left-hand column) it says:

Power Supply: 2 Type AA alkaline batteries.

Does that answer your question?

 

[SpaceCowboy2071]

If you look at the Spec (second page, left-hand column) it says:

Power Supply: 2 Type AA alkaline batteries.

Does that answer your question?

Doh! It totally does! Thanks, that does answer my question, the thermostat runs on batteries. I guess they went dead the same time the new boiler was installed, just in time to make me doubt that the installation was done properly.

Thanks again!