Disconnecting a room thermostat - ???? Advice

[bengasman]

Biggest boiler manufacturer in the uk.. Think why a roomstat would not be needed

No roomstat needed? Only reason I can think of is that they break down so often that they are energy efficient even without a roomstat. All jokes aside, I can not think of any reason as part L2 says categorically: need a roomstat.
Whatever clever system you design, the boiler will never know the temperature of any area other than the one it is in. unless you think of those boilers that come with an integrated wireless roomstat where you only have to bond the sensor. I still count those as a roomstat.

 

[ratonnastick]

isnt the requirement a boiler interlock , something that turns off the boiler when there is no call for heat. only way i can think of is a room stat or stats. Any system with trvs and a bypass can run constantly.

 

[namsag]

Yes the requirement is an interlock not a roomstat although this is the how the vast majority of system achieve an interlock..
Baxi solo HE range and Baxi HE combi range achieve this with a flow switch which as the last trv shuts off the boiler senses no flow at all and shuts the pump and burner off instantly.
There manufacturers instructions say this meets part L requirements and no roomstat required but pump must be wired direct to boiler..
And as we are always told MFI`s over ride all other rules

 

[ratonnastick]

surely thats a fail safe control and used as a control would cause the boiler to overheat and eventually damage the boiler.

 

[namsag]

Obviously not if Baxi are putting it in print and saying thats how to fit them. They must have built the boiler to accomodate the heat on turn off.

 

[ratonnastick]

Clever little boiler senses the flow temperature and turns it off when it goes over the set temp then shuts down and goes into pump overun.

 

[bengasman]

Manufacturers instructions override general rules, so if they say it complies with part l, so it does. I wonder how long the full warranty, parts and labour, is on this setup. I can see how it works, and also how it can go wrong.
Demand, pump starts, sensor proves, fan starts etc. now the pump also has to prove there is NO demand. Not a model I would like to fit.

 

[nickso]

is this the baxi flow switch that is stuck to the side of the heatex we are talking about?

they are about as reliable as a chocolate fireguard.

 

[namsag]

OR is that as reliable as BG own brand roomstat . i know what is the most reliable and if your honest so do you

 

[nickso]

OR is that as reliable as BG own brand roomstat . i know what is the most reliable and if your honest so do you

not being funny namsag but i dont think the BG roomstat is unreliable. i wasnt comparing it to the flow switch either.

ive changed far more of those flow switches than i have roomstats....good deal harder to do and probably more expensive too.

again not being funny but how many bg stats have you changed?

 

[namsag]

At least 50 percent of the danfoss type. That ones that need the neutral everyone at least 5 degrees out

 

[nickso]

i wasnt aware bg were using danfoss.

i thought you meant the acl/invensys ones.

 

[namsag]

yep your right nickso i meant the drayton(acl) not danfoss