Central heating taking ages to come on

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this is so annoying. We turn on the heating and it takes ages to 'kick in' it just does nothing then will suddenly start working.

it sometimes takes up to three hours to start, dp has altered the pressure which seems to have helped heat up the radiators but it just literally takes ages to get started. any ideas? it's a potterton combi and has had quite alot of work done on it already

is there one radiator that heats up when all the others are cold?

Or do they all warm up at the same rate?

Does the boiler start firing as soon as both the timer and the wall stat call for heat?

What does the wall stat look like?

yes sometimes the one nearest the boiler heats up long before the others. the boiler seems to fire up a long time after the thermostat is clicked.

the wall thermostat is bog standard dial

turn off whichever radiator(s) heat up first and see if the others then warm up.

Your radiators may need to be balanced.

Or the pump may be worn out, or circulation may be clogged. When warm, are the radiators cold at the top, or in the middle, or at the bottom?

that doesn't make much difference. apart from one which is hot at the bottom and colt at top all the rest seem quite hot, just taking ages to come on.

"hot at the bottom and cold at top "

that one needs bleeding. What colour is the water that comes out?

How old are the radiators?

am scared to bleed them to be honest, when i've done it in the past it's always caused the system to lock out and i've had to call plumber

they were put in 1999

after bleeding, you might need to top up the pressure.

Can't think of any other reason for it causing a lockout.

Does your room thermostat have a button with the word "save" on it?

1999 radiators might have a sludge problem. It is possible to do a DIY clean if you are fond of plumbing.

not really, but is it easy?

you need to find the drain cock, because you will be draining out the dirty water; and the filling valve, to fill and pressurise it, and to bleed all the radiators during refilling.

You also have to add a cleaning chemical near the beginning of the process, so that you can drain and rinse out the loosened sediment a few weeks later, and to add a corrosion-inhibiting chemical on final fill.

If the drain cock is jammed or perished, you may have to take it off and fit a new one.

It is easier if you have an unpressurised system with a small feed and expansion tank in the loft.

You need several large spanners, a bleeding key and possible a radiator wrench, and a hosepipe.

oh dear that sounds involved! perhaps i should call someone..

if you call a pro, they will probably want to sell you a powerflush for some £hundreds.

Properly done (it should take about half a day) it is more effective than a DIY chemical clean, but of course, not as cheap.

Ask how much extra it would be to fit a system filter (which will trap particles and prevent the risk of sediment in future) at the same time.

Usually these boilers have a basic filter inside the return connection on the bottom of the boiler. If this becomes restricted it can cause the heating to heat up very slowly.

oh that's interesting summer thanks. thanks for all advice will research prices now!

Sounds like it needs a good clean out to me. We bled all our radiators and put ton of crap into boiler which then stopped. Cue clean and new filters!