We have a fairly large four bedroom house,and may soon require a new boiler,since the old one (Glowworm 85/100)is getting rather old,though very reliable.Until I am sure of the reliability and suitability of the possible replacements,I will not change it.We recently had a small modification to our system (removal of a Drayton valve on the output of the gravity feed to the hot water cylinder which was blocked with sludge.The boiler seems now to be much more efficient.From comments made by the plumber,I would like some balanced advice.
1)He recommends a new type of large Combi boiler (Valiant) on the grounds that it is cheaper, easier to install, less disturbance,etc.He thinks our water pressure is adequate to provide for a conventional shower.He also says that another advantage is that we will not need cold water tanks in the loft,or a storage hot water cylinder. We think that there are disadvantages in that the system has to be pressurised,with possible problems if small leaks occur,our mains pressure fluctuates quite a lot (shower problems?),and that baths take longer to run in very cold weather.2) He indicates that current building regulations require the retro fitting of thermostatic radiator valves on all radiators,which he says he can fit easily,and also recommends some form of wireless control for the system. All sounds too complicated for me and too much to go wrong.What are the minimum controls required these days to improve efficiency of use?
3) He says that a new condensing boiler operating in a more conventional system with cold feed+ expansion tanks together with a new hot water cylinder ( we have a Primatic cylinder at present ) will be three times more expensive,but we are prepared to pay this if the system is reliable and without disadvantages.4) One other thing concerns me.Condensing boilers have had a bad press over the last few years-rotting internal components, blocked condensation pipe outlets in cold weather,need six monthly servicing to keep efficient.I am still of the opinion the design of these boilers is still in its infancy.I do not wish to install a new system and have a load of hassle.
5) I am sure that our radiators are partially blocked with sludge,but wonder how effective power flushing is.I understand that all that happens is that a powerful pump is installed to push the sludge around and out of the system.Doesnt that just push the sludge to collect at other points.The other alternative is to put in chemicals to dissolve the sludge,but understand that these do not work that well.So you can understand why I wish to hang on to my existing siystem since it has served us well for over 45 years. I am sure that the boiler may be on its last legs ,the radiators and radiator valves are becoming bunged up with sludge,but I am still of the belief that if it is not broken,dont fix it -unless of course we have to.
Michael