Question about new boiler

[Steve]

I have had a Baxi duotec 28 fitted, no external controls, just a digital timeclock and the standard temperature controls for the outputs.

I have 6 radiators. 4 of these have thermostatic valves.

I have noticed just recently, the boiler seems to cycle a lot (igniting say once every 10 mins) and this co-incides with the times when the 4 radiators are closed, so all the heat is being pushed through 2 radiators.

The 2 rads without TRVs are in the bathroom and hallway, which really do need heat all the time, as they are the coldest rooms in the house (lots of external walls, front door in hall, only a towel rad in bathroom).

Is this cycling doing any harm?

I had thought about having a thermostat installed in the hallway, so when this is at temp, the boiler shuts off.

Also, I have read that the return water should be at around 50 degrees for maximum efficiency, is this right? How do I tell? The flow is set at 65, though I guess the return will vary depending on the number of rads open.

 

[dcawkwell]

You say the 4 radiators have shut down therefore you must have
these set fairly low.

If the boiler is only driving 2 radiators say if these add to approx 2-3kw
the boiler will have to cycle on and off as the radiators will not
be getting rid of the heat that the boiler is supplying.

The wall thermostat will only cut the boiler off once it senses the temperature
around it has been reached otherwise the boiler will keep going.
It sounds as if the radiators in the hall and bathroom are insufficient
to provide the heat for the rooms. I suggest upgrading them to larger
ones. Towel rails are hopeless and provide very little heat. The white ones actually produce twice the amount of heat like for like that the chrome ones do. But for real heat in a bathroom normal panel radiator required.

Bring the flow temperature up to 70 degrees to get a little more from the hall and bathroom radiators.

 

[Steve]

Ah well I have a chrome towel rad! I did consider having a radiator in addition to it, but just got a bigger towel rail instead.

My ideal system would have a zone valve for upstairs and one for downstairs, and the towel rad on all the time there is demand from either zone. Each zone would be controlled by a programmable stat/timer. But this would be very fiddly to install in this house!

I do have the rads set at 3 or 4, but I dont trust them 100%, sometimes the living room creeps up to 23 degrees, then I have to change the setting down a notch. One of them seems to completely shut off the rad unless its on 5, regardless of room temp.

When the boiler was fitted I did have the hall rad made a size bigger, it cant be any bigger for the wall its on, unless I have one fitted on the landing too.

 

[transam]

Should have some type of boiler temp "interlock" fiited generally a room stat

Dare say if you look in the log book that came with the boiler & has been filled in , it will ask the question has boiler or control interlock been provided ( or words to that effect?)

And the answer is ??