Preventing airlocks in new central heating.

[steve.c]

I am planning on having a combi boiler installed and have decided to replace all pipework and radiators myself to keep the cost down. I have a couple of queries if anybody could please help me out. I will be fitting 4 upstairs radiators and 3 downstairs and running all pipework into the airing cupboard for when I get round to having the boiler fitted. The only thing I am not clear on is if I should fit air vents on the pipework to the downstairs radiators (I believe this is a place where air locks can form)and if so what type should I use. I have seen bottle type ones,or small automatic ones. If it is the case that I do need to fit these do they go on the flow or return or both. Any help appreciated.

 

[Jezzy]

There are air vents on the new rads. why do you need any others with a combi boiler?

 

[steve.c]

Thanks for the reply. The only reason I ask is that my present heating runs a off back boiler and unvented cylinder. I had to drain down the system last year following a burst and when the system was refilled an airlock formed and I had problems getting the heating back on. I spoke to a plumber at the time and he told me a common place for airlocks was at the high point of a vertical run of pipe. Thought maybe fitting vents would prevent any such problems should I have to refill a new system at anytime in the future or will the radiator vents be enough.

 

[BenRL]

If you have an unvented cylendar, then why get a combi????? unvented cylendars are **** hot at hot water flow rate. Just get a system boiler, it will still be pressurised, and you will have no airlocks. AND....... cheaper on gas

 

[steve.c]

Unvented cylinder is in loft and want to convert it at sometime in the future. We are limited for space and am quite reluctant to get a combi as you are quite right the water pressure is great but the boss has made her mind up that we need more space. (Perhaps she won't be so pleased with herself when the combi packs up every winter).