C/H plumbing

[akist]

We are setting out the pipes for the C/H, and due to the size and construction of the house we are ending up with a somewhat "star" system, for example there is a central run which then gives off smaller bore into 1 or 2 radiators that happen to be close together, then the central run continues to some other part of the house where there is another branch etc. Some branches also go upstairs to feed a couple of radiators each.

I would like to ask, as the runs are long, I have some straight long runs that are sloping downwards a bit. Is that a recipe for disaster (air trapped) ?

Secondly, is it OK to go up 1.5m and then come down into a radiator? The plumber said this is very bad because air will get trapped in that section, but can't I just have auto-air-bleed valves at the highest points? The reason I want to go up 1.5m and then down into a radiator is so that I can hide the pipes better. Otherwise I would have to run them on or in the floor which is a major pain.

 

[Madrab]

AS long as the system is sealed then airlocks on the main system shouldn't be a problem, just make sure the rads are bled systematically. You want to minimise any of the system pipework being higher than the highest radiator or higher than the radiator or the main F/R on that branch (if you see what I mean), exactly for that reason.

Auto air vents are ok when they're new but I've yet to find one that hasn't leaked even a little over time. Air will always find it's way to the most PIA places.

 

[Exedon]

As above avoid auto air vents like the plague.
Use manual ones instead, assuming sealed system as it's new should clear air fairly easily.

 

[akist]

Fantastic. There is just two radiators, that I must feed going over a low doorway (1.7m high) or at floor level. If at floor level we will be tripping over the pipes. If over the doorway I will need an air-bleed valve, which I should get a manual one.

 

[Madrab]

Never paint over vents or place them anywhere they will be sealed in without understanding that it may need to be accessed at some point later, destroying anything that is covering it unless access is built in.

 

[Mottie]

As above avoid auto air vents like the plague.
Use manual ones instead, assuming sealed system as it's new should clear air fairly easily.

The Spirovent Deareator that I fitted to the outlet of our boiler (sealed system) has been working brilliantly since fitted 5 years ago. It got every last drop of air out of the system that constant bleeding wouldn't.