Pipe Run?

[gilest]

Hi - Im Installing a new boiler upstairs in my house, and to connect the CH Flow and return I am going to have to take the pipes on a route where they will rise 4" then fall 4" under the floorboards. this is on the main flow and return lines (before any radiators feed off) - Is it ok to do this or will this cause an air block - I havent got much room to add a bleed valve - and anyway It would be under the floorboards!

 

[ArtfulBodger]

If you used Hep20 for this bit, assuming your are far enough away from the boiler, would it make it any easier?

 

[Bahco]

I wouldn't think the 4 inch rise on your pipework would make any difference if you are fitting a combi boiler as the flow and return pressure should be enough to negate this .
The rules are however that a air vent should be placed at the highest point to release any trapped air but I would be inclined to go ahead due to the small rise in height of your pipework.
I must say that I am puzzled by why you need to run your pipework like this and would have a look to see if there is an alternative route

 

[ChrisR]

You could install "finger" vents, which are very small, so that you can get rid of air on installation/first fill. After that any air which collects will dissolve into the water eventually.

Boiler primaries often have to go up, across a ceiling and own the other side, and they're ok.

If your heating system is VENTED though, you're stuffed - the vent has to rise continuously from the boiler.