Cold C/H - Boiler cycling

[zxzqz]

Central heating at my mums has been gertting less and less effective over the years. Rads now dont really heat up much at all and impossible to get the house warm. Recently I think the system has totally clogged up somewhere. The boiler fires up for a few mins then shuts off. This keeps repeating. I'm guessing nothing is flowing so its just overheating and shutting down.

I remember checking the pump at some point and it seemed to be spinning so don't think it's that. Plumber has suggested powerflush which probably makes sense as I don't think any maintenance has been done to the system since the house was built 30+ years ago.

One quote for powerflush was £700 to use sentinel 400 and leave in for a week. Next quote £350 to do in a day and said the other guy was just leaving in for a week so that he could charge for two visits! I assume the second would prob use stronger chemicals?

Fine if so however we know from neighbours that some pipes are buried direct in concrete so could be weakened. Could the weaker chemicals be better in this situation and given that the system is pretty old? Or does it not make much difference?


We also want to replace the remaining original radiators as we have a couple of newer ones that we fitted quite a few years back that are much better. First guy also quoted an extra £2200 to supply and fit 7 rads (think some are longish) and a new towel rail. Sounds quite a bit to me but used him before and was good.

Have always had a problem with switching hot water on automatically turning upstairs heating on too (annoying in summer!) but one prob at a time I guess...

Long post but any thoughts on course of action and prices appreciated! Many hours of googling and reading this forum only raised more questions...

 

[Agile]

You seem to have had some seriously expensive quotes there.

You dont say where you are but in London I quote £300-£350 for power flushing and get very few jobs so someone is doing it much cheaper.

Burried pipes in concrete are a real danger!

Many will not go near it !

I would be inclined to power flush it but only with a smaller amount of X400 which is milder than the correct X800 which is usually use for power flushing.

Leaving X400 in the system for a week is far too little time, it takes 4-6 weeks to work.

Tony

 

[zxzqz]

Thanks for the reply - that's cleared up a few things for me.

Bad news about the pipes.. Oh well, needs sorting so will try it and see what happens. Hopefully it will play nice and not leak.

Yeah thought high, trying to get a few more quotes. Think my mum may end up going with the first guy anyway for powerflush even though expensive. Apparently he knows the properties well from working on neighbours places and has possibly powerflushed a couple before too. Might be useful i guess given the risky pipes, will have to decide.

Perhaps we'll get that done first and then look for a better quote for the rads as that should be a more straightforward job. Hopefully things will be warmer after the flush anyway.

Northwest btw, harrow-ish. And thanks for the final tip on the x400!

 

[Agile]

You should look at the colour of the water first. If reasonably clean it may not need power flushing anyway.

Then check the pump impeller and the torque using the "finger test" as described in the FAQ on this site.

Tony