Boiler keeps turning on and off, house not getting to temp

[danoid]

Now sorry. I wouldn't say they are 100% spot on, sure I read it should be 12oC difference between flow and return by the radiator.

But followed that whacky guy on YouTube (plumber parts) close upstairs fully then open by a quarter, have downstairs almost fully open, which has done the trick. Didn't help someone upstairs turn the on off dial and lockshield covers around

 

[Agile]

The flow pipe is much hotter on boiler than the return.

Or are you saying the boiler on off is fine and meant to turn on and off? And not what I thought, which is it constantly on until it gets to my desired temp

There should be about 11 C difference on a non condensing boiler ( and about 15-20 C on a condensing boiler ).

Sounds as if yours needs rebalancing to achieve 11 C for your old non condensing boiler.

As I said before, the boiler will go off and into anti cycling delay as soon as it reaches the set flow temperature. Do you not learn?

Tony

 

[Scarum]

I am suspicious of anyone that starts a sentence with "So".

So, when the temperature on the boiler thermostat is met it will turn off, regardless off the room stat. If it didn't there could be a melt down or an explosion which would be rather inconvenient.

With this in mind, if the rad in the room where the room thermostat is located is turned down OR if the rads downstairs are not balanced correctly or if you have a flow problem you will get this problem, I am certain! Tell me otherwise please.

 

[Scarum]

I take too long. I'll shut up.

 

[danoid]

Thanks for that so sounds like it's a goodun now then. Just minor adjustments to make it 11oC

Many thanks for your help

 

[Agile]

For all those avid readers who like to learn all about heating!

In this case with a non condensing boiler having a too wide delta T on a non condensing boiler will not increase boiler efficiency.

But it also has another very bad effect! It reduces the average temperature of the radiator and reduces its heating output. He needs all the heat he can get!

Say flow and return are 80 C and 60 C then the average rad temp is 70 C.

But if correctly at 80 C and 69 C then the average rad temp is 74.5 C

Why this apparently small increase is so important is because its the temperature ABOVE the room temperature that determines the rad output power.

Room at 20 C then with rad at 70 C the difference is 50 C.

Room at 20 C and rad at 74.5 C the difference is 54.5 C so an increase of 9% ! He needs every little bit he can get.