[OpenTRV-interest] System queries (Was: Update: OpenTRV Limited is now Vestemi Limited)

[Simon Hobson]

Firstly, as a matter of general mailing list netiquette, please do not start your own thread by replying to an unrelated email. It causes confusion with the archives and clients that thread messages. Doubly bad is hijacking an unrelated thread and not even changing the subject !

Daniel Pocock <daniel at pocock.pro> wrote:

> I acquired a house in Dublin, the heating system appears to be older
> than me.  It is a Potterton Kingfisher 2 CF80 with a 2-wire control.
> There is an ancient timer switch in the kitchen and an ancient
> thermostat in an upstairs bedroom.  Given the antiquity, all this would
> be replaced in an upcoming renovation but I'd like to start
> experimenting with the technology now for anything I can replace easily
> myself.
> 
> The plumber told me 6 of the valves are not working and the pipes are
> old gun barrel and difficult to work with.  So I thought next time he
> visits, he could put in one or more of the Radbots for me.
> 
> I had a look in the FAQ already and I still have some questions
> 
> Are there specific requirements for the type or size of the radiator
> pipes it can be attached to?  For example, I saw this picture[1], is the
> part labelled "TRV Valve Body" included with Radbot or the plumber can
> install/replace that if necessary and then I put Radbot on top?

No, the valve body is not included. They usually come as a set with the valve body and thermostatic head in one box, but you can buy the valve body separately. IIRC the radbot fits valves with a 20.5mm thread, but can fit other bodies with adapters.
There are no special requirements for the valve, so just have basic TRCs fitted (make sure they have 20.5 mm threads for the actuator head fitting), you can use them as basic TRVs right away and try radbots later.

> Is it only wireless or if I am rewiring the house, can I put RJ45
> sockets near the rads and use PoE in future?

It's wireless only, but in previous emails it has been suggested that it wouldn't be hard for someone with the right knowledge (which excludes me) to swap the radio module for something else (eg ethernet). I too would prefer PoE ethernet as an option - it more or less removes any constraints on power, and makes two-way communications much easier.

> Are they suitable for wet areas like bathrooms?

I stand to be corrected, but I assume they would be OK for a bathroom, but somewhere properly wet like a wet room.

> For the spares you mention, is it likely they will have any issues that
> may cause frustration for the plumber?  I don't want him to get a bad
> first impression.

The radbots don't directly connect with the plumbing, only the TRV body. So as long your plumber can wrangle a modern valve onto the prehistoric pipework then there should be no problem.

> Is it possible to install Radbots and adjust them manually before the
> central control system is installed?

Each valve is autonomous and does not actually take instruction from a controller. You just install the batteries and it does the rest - working out  when the room is occupied etc. When it determines that the room is unoccupied then it drops down to it's night mode (18˚C IIRC), when it determines that the room is occupied then it sets itself up to the temperature set by the dial on top.
The primary target was/is those properties with no effective controls and/or where the users just don't understand how to use them (which is most people IME !) Hence they are designed to be autonomous and simply screw onto a standard TRV body - making them easy to fit, and easy to remove and take with you (many of the target market are in rented properties).

The boiler controller is "the cherry on the cake" - though highly recommended. Without it, the boiler will simply run all the time, or when the time clock says to run - pumping water round and firing up the burner every time the temperature drops a bit. The controller's sole function is to turn the boiler on/off - it doesn't control the radbot heads.

> You suggested in an earlier email that a bypass valve is essential.  The
> plumber tells me there isn't one and it is not worth installing before
> the renovation.  If I only have Radbots on some radiators and other
> radiators with older valves are always left on, can I get by without
> having a bypass valve?

Yes, on almost all systems a bypass is essential. Without it, as thr rad valves close down (either manually or because they are TRVs), the flow through the boiler must reduce. There are no boilers that I am aware of which allow such a reduction in flow rate - hence there must be a bypass to allow a satisfactory flow rate through the boiler.
Some boilers have a bypass valve built int, otherwise it must be part of the system. It can be as simple as a bypass loop with a fixed valve, or a radiator that is never turned off, or preferable is a pressure sensitive valve - the latter is effectively a pressure relief valve that only opens when the pressure in the system increases as the pump tries to force water through closed rad valves.

> Do I need to use the boiler controller box or can the controller
> software run on any Linux device such as a Raspberry Pi, Freedom Box or
> micro server with a GPIO to the boiler wires?

You would have to engineer your controller software for something like the Pi - it would be "very very overkill" for what is needed. TBH I'd suggest just sticking with the standard controller - it'll be a lot less hassle.