DIY Doctor UK DIY Forums

Our ceiling height is 2550 mm.

I wanted to fit 250l unvented cylinder and boiler in airing cupboard which is 1000 x 800. Plumber is suggesting it is not possible to fit both in airing cupboard due to the height of unvented cylinder (1738 mm).

Hence he suggested to put unvented cylinder in loft.

He is also saying that there is risk of cylinder toppling in open loft without any wall support on sides. Hence he is suggesting to go for horizontal cylinder. I have an impression that horizontal cylinders are not as good as vertical ones.

I am not sure about the risk of cylinder toppling?

Any cylinder is heavy when full of water, the supports for mine failed and needed emergency work to repair it.

Vented needs height, unvented does not, it could be outside in a lean to. What is more important is can your beams take the weight, ask the plumber to view his calculations and likely you will find he does not know how.

No all bad, ask me to calculate cable size for volt drop, yes I can do it, but in the main I know from past jobs if likely near limit or well within and likely will not calculate if well within.

But clearly he thinks it is on the limit, and if a horizontal tank spans 4 beams and a stand for a vertical also spans 4 beams then it's the same weight per beam.

Personally would not fit unvented as don't want the cost of annual inspection.

With oil combi boilers don't really work, as the boiler can't modulate much, so really need a cylinder, with gas, unless going to fit solar panels, may as well have combi boiler and not bother with a cylinder.

The problem is, with a combi boiler fitting OpenTherm thermostats for central heating is easy, no motorised valves outside boiler, all is inside the boiler, it is simple, once you start adding motorised valves the system becomes harder to plumb, wire, and set up, and the heating engineer earns his money making sure the system works.