Under floor heating question.

[badgeraudio]

I'm looking at installing the poly pipe overlay system in my 1994 property when i knock a couple of rooms together.
The boiler is a brand new ideal system boiler on an s plan with a non vented tank.

My understanding is that the there will be a new 2 port valve and thermostat to run the boiler on the ufh circuit when required.

The blender valve on the manifold will get the V hot water from the boiler and mix it with the cooler water from the loop return to the preset temp for the loop flow.

Now when the loop is up to temp, the blender stops adding hot water, but the blender pump carries on circulating the water through the ufh.
But the boiler is still turned on, but not circulating the water anywhere as the other 2 span valves are shut.

Can the blender valve not turn the boiler off????

Will it not build up pressure and go wrong??

 

[Agile]

Some blender designs return some hot flow water to the boiler return.

But the system would have an auto bypass to maintain some flow through the boiler.

Ton y

 

[DP]

In my son's place, a mix of radiators and underfloor, I fitted a three port valve so no bypass needed (though fitted if later system alterations carried out)

 

[dilalio]

Controls will shut demand for heat from boiler down, when stats are satisfied. Primary system pump will overrun to dissipate latent heat in primary circuit.

 

[badgeraudio]

So it looks like it will be safe, as I guess it should be.
It just wont be as efficient a system as it could be with the boiler kicking in and staying on when its not 100% required.

Ahh well.

Cheers

 

[Underfloor Guy]

As has been said earlier; thermostats & controller will control when pump & boiler runs, boiler will fire burner as required based on temperature differential of flow/return, injector/blender will "draw off" hot water from the boiler circuit.
So even if the boiler is running it may only be the pump/fan running not burning gas. If I'm explaining that correctly