Are your radiators on yet?

I would not replace the system either. New boilers may be more efficient but have a reputation for unreliability.

It is good that you don’t have to bleed the radiators but it is generally very easy and quick to do.

If they need bleeding a lot then either air is being sucked into the system, gas is being generated due to lack of inhibitor or you have a leak and are constantly adding new “gassy” water to the system from the header tank if you have one.

Thanks for the suggestions, rarrar. I had the same thoughts when I moved in to my house 30 years ago, but I never managed to find out why my hall radiator needed to be bled every month or so.

The system had inhibitor and I have replaced it twice without any change. If part of the ‘air’ in the radiator is hydrogen produced by corrosion then there is not enough to burn, and there is very little sludge in the radiators. I am losing little water because I can turn off the header tank supply for months and it does not empty. It is a mystery but fitting an automatic bleed valve to the affected radiator means that it no longer needs to be bled.

I hope that your suggestions might help someone else.

@Wavechange.

My parents’ bedroom radiator always filled with air very fast from the day it was installed in 1969 until long after my dad died when in 2005 my mum asked the plumber who services the boiler every year about it.

The plumber explained that air will get sucked INTO the system through pin-prick holes or microscopic gaps in thread-seal which are too small for water to leak out.

He looked at the affected radiator and decided that right from day one the blank plug in the top of the rad at the opposite end from the bleeder has not been tightened quite as far as it should.

A quick nip with his spanner and, 26 years after installation, all the air gathering stopped like magic!

It just could be that your hall rad (or a pipe joint very near to it) has such a microscopic ‘leak’.

Dave D

Thanks for the suggestion. Air can certainly be pulled into a CH system when the pump is running.. My parents’ upstairs radiators could not be bled unless the pump was switched off, and opening the bleed screws would pull in air.

I’ve given up trying to fix the problem and my one automatic bleed valve keeps the offending radiator full.

It is not necessarily difficult but you will need to do a bit of reading and some preparation, such as flushing the system. Inhibitor is best added to a new CH system, following the instructions carefully.

It is well worth doing because without inhibitor, steel radiators will gradually corrode internally and fill with black sludge that can make them less effective and cause problems with circulating pumps, etc. Black sludge can make a horrible mess of carpets if radiators have to be removed or start leaking due to corrosion.

It is important to record what inhibitor has been added because topping up with another brand could cause problems. Label the system with what has been used and when it was added.

You will find cheaper products that will do the same job but I have no idea if they will make much of a difference. If they did, I think they would be recommended more frequently.

If your existing boiler is still in serviceable condition and reasonably reliable, I suggest you keep it. New boilers are more efficient but many have found them unreliable and expensive to repair.

I cannot comment about the radiators but you could find that they are worth money if they are very old and in reasonable condition.

Hello Jacqui.

Sarah from Which? Local, here.

I’ve posted your comment in our forum here.

Our community includes a number of central heating engineers so keep an eye on the thread for updates!

Jacqui

I cannot see any scientific basis for a difference in costs. There may be a difference in how quickly they warm the rooms, but the same would apply if you compared small and large radiators. Here is a link to what looks like reasonable information. I know nothing about the company and the page just turned up using a Google search: https://www.castrads.com/frequently-asked-questions/buying-cast-iron-radiators/are-cast-iron-radiators-as-efficient-as-modern-radiators/

If someone has sold you new radiators on the basis that they will save money, I would be very interested to see their explanation.

I think you could possibly find that the new boilers simply cannot heat up the old rad’s in a reasonable time nor keep them properly hot in very cold weather. New boilers are actually not at all efficient unless installed in very specific ways with very specific heating system components. I’m not a boiler engineer but my highly respected plumber and heating engineer tells me, and I’ve heard it said on consumer programmes like You and Yours and Watchdog, that new boilers will only work efficiently or effectively if they are installed into “ideal” systems.

Therefore I suspect that the answer to your question is that new rads alone are not more efficient and that the new boiler alone is actually very inefficient, but if you replace both boiler and rads you **might** manage to achieve a slight efficiency saving and maintain a reasonable heat-up time.

Wavechange’s original answer, which you did not like, is actually the best advice: don’t change the boiler. Your new one won’t be designed to last more than 8 years, and quite possibly won’t even do that long, it will be unreliable – especially heating up old style rads – at the side of the existing one and could end up costing you far more to run than your existing one.

Even the boiler manufacturers openly admit that you will never save enough on gas in the boiler’s life time to cover the cost of having it put in; you’re on to a loser if you are doing this to save cash.

If you have no choice but to replace it then I think you might well need to replace the rads too to avoid multiple future failures.

Hope this helps.

Sounds like your rads need balancing, not flushing.
Have you had any changes made to the system lately? If so I’d bet my bottom dollar on it needing balancing.
Power flushing is just a rip off an often causes leaks.