Hot water problems & rads get hot when only hot water on

[Radioactive Kid]

We are currently having some ongoing problems with the hot water taking a very long time to heat up, also we noticed recently that while we have had the hot water switched on the radiators seem to be coming on?
British Gas told us that although the boiler is very good for it's age, because the system is quite old it's struggling to heat the water & rads if we have them both on at the same time & also that the diameter of the pipes were quite small and it could be scale damage? (could all this be true?)

Just to give you all a picture the boiler is a floor standing Ideal Mexico RS65 in the kitchen of an old 3 bed end terrace, there are 8 rads throughout the house and i am informed the whole system was installed about 1985!

Unfortunately a new system will have to wait a while, as the owner of the present one is my girlfriend whose mother has just passed on.

 

[Slugbabydotcom]

Could be a few things
Maybe your boiler stat needs turning up or is faulty
Maybe your pump speed is too low or your pump is weak or inefficient for some other reason such as blocked pipework or sludge.
Could be that air needs venting from near the cylinder.
I could rattle on for ages about whats possible so its best to get another opinion or do some investigative work.

 

[DP]

For this one, I would start by servicing the boiler. Service means removing the burner, cleaning it, cleaning the pilot assembly/ injecter, sweeping the heat exchanger with a flue brush and reassemble.

Then I would check flow and return temperatures at various points to establish is blockages )sedimented or airlocks) exist.

If the system has gravity hot water zone, do not expect miracles as often this is piped in 15mm. Anotrher consideration for aforementioned is seasonal temperature. Your radiators will be needing 85 degrees of heat to achieve designed room temperature. With rads on, gravity hot water zone gets lazier, so hot water takes longer to come up to temperature.

I would think twice before embarking on purchase of a new (mostly combi) boiler. Improve on what you have. It will serve you well.

 

[Ron Gamma]

I had a similar situation with a '64 build property. It has an ancient and inefficient boiler in a shed outside the back door and used to be a gravity system but had been fitted with a pump. The h/w cylinder was in a bedroom at the opposite end of the house and bore a kite mark dating it to 1973 at the oldest. We couldn't get sufficient hot water out of it and the rads were always on heat unless the TRVs shut them down. I was using approx 4.5 units of gas per day. Fortunatley I found a leak on the cylinder and decided to change it.

Friendly family boilerman turns up and says to fit the new cylinder in the garage so that it is nearer to the boiler. Anyway, several ££ lighter I have a nice new cylinder full of piping hot water. The old cylinder was chock full of scale and the heating coil within was not transferring heat effectively. ££ well spent !

Still had the problem of the rads coming on so we had another look at the "S plan" setup and discovered that there was no room thermostat. It had been wired to run the heating permanently unless the TRVs shutdown. Only the cylinder stat remained wired. Fitted a new wireless room stat and bingo - what a result. Gas usage for same winter period is now down to 2.9 units per day, falling to less than 1 unit during summer.

Next job is to fit more efficient boiler (Promax HE seems to be one of higher rated according to SEDBUK) and gas bill should be back under control.

I agree that sticking with what you have and improving it works. You can fix it in stages as budget/time allows.

Don't go Combi - its nice to have an immersion as a backup. Many of my colleagues have combi systems and are always whingeing about no hot water at all when it breaks and takes days to get anyone out to repair it.