vokera mynute error condition

[Boilerman2]

Just a thought - you say that the by-pass on your system is a single rad without a TRV? - surely in AUGUST the boiler will be running hot water only? so how exactly is the pump over-run going to work, if the motorised valves have closed? you will have effectively NO BY-PASS. you sohuld fit an Automatic by-pass valve, between the pump and the the motorised valves flowing directly to the boiler return.

 

[picasso]

because its on a y plan it doesnt need a bypass.

 

[ianmcd]

will depend on the make of the mid position valve some are spring return some are motor return if is in HW only mode when stat or time clock are satisfied then no by pass will be present if pump over run is activated

 

[picasso]

mmmm if its in the hot water only position, the flow will run through the cylinder coil and back to the boiler aka bypass

 

[ianmcd]

I agree mate but will depend on the distance between the Boiler and the cylinder M.I. as always are the best source of reference, if the cylinder is at temp then only heat loss through pipework will count as your by pass so obviously will depend on length of pipework and whether it is lagged etc. you seem to know your stuff and think we both know the problem with this boiler isnt anything to do with the by pass, was just saying that not all mid position valves dont require a by pass agree in most cases they dont but some do depending on the heat loss calcs boiler manufacturer will usually design free of charge if someone asks

 

[oldterry2]

The system is a sundail Y. In this system the motorised valve moves to feed the hot water in the absence of any demand. As the hot water tank temperature is always likely to be cooler than the boiler output temperature in any normal situations, this will act as both a bypass for the water flow and a heat sink to dump any excess heat.

Note that the original error condition was "no circulation" and not "excessive temperature" - they are different error states on this boiler.

 

[oldterry2]

Just to bring everyone up to date with this old thread, in case someone else has the same problem.

After a few months with the replacement thermistors, the problem recurred. During the following months, Vokera looked at the boiler a number of times, checked things, replaced the thermistors again but to no avail, the problem kept recurring. During this period, my installer swapped the pump, made a piping change, and the motorised valve head was switched (though that was due to the head dying). Eventually, in the spring, Vokera swapped the master logic board and there have been no problems in the following six months.