My boiler has packed in, the heat exchanger has failed and the consensus is that was due to sludge, gunk in the system, also consensus is would be better to pay a bit more and get a new boiler and guarrantee rather than getting it repaired.

My system is a regular open-vented system. The benefits of a sealed pressurized system have been explained to me and my view is I would like the central heating pressurized but not the hot water system.

The reason being I do not want the hot water system pressurized is I am concerned about additional noise from having water pipes all pressurized, and all the extra cost and hassle of having to replace the hot water cylinder.

The reason being I do want the central heating system pressurized is the system seems suspectible to air and sludge, there is a problem getting radiators high up in house working. And it makes sense to me to fill the system once, and having it continually reuse that water for the heating system.

But I am unclear whether it would be better to get a System Boiler or a Regular Boiler with kit for this purpose. System Boiler seems to only be when heating and hot water is pressurized, regular when neither is.

I understand that a regular boiler can be used with a pressurized sealed heating system via use of a external pressure balloon ectera. I am not clear whether you can use System Boiler if you are only going to use it for heating water used in the central heating system and not for directly heating hot water.

I am not sure if you can use a System boiler in a non-pressurized system. i.e if a System boiler is installed, and then we find pipes are too leaky or mains pressure not enough would that then mean System Boiler was no use or could it be used liked a regular Boiler ?


I was in the boiler business for 40 ears and am having a hard time understanding your question. Here in the USA we almost always, install pressurized hot water heating systems. I do not understand the terms you are using, "system boiler' or "regular boiler". You also said that your system is a regular open-vented system. We had systems we call open or vented long before I started in the profession; (the expansion tank was an open and vented tank, mounted at the high point of the system with a drain line that ran to the basement). Sometimes, it is hard to explain what we each see when different countries explain things differently. No offense intended.

  • Okay, but aren';t there any UK based experts on this site, i find explantions easy enough - boilerguide.co.uk/types-boiler-explained but it is unclear to be why a system boiler doesnt need cold water tank and regular boiler does. In fact further digging shows this may be bs and that actually there is no difference between system boiler and regular boiler with pressure balloon kit, and in either case you could optionally have water system as pressurized or non-pressurized. – Paul Taylor Nov 30 '18 at 13:59

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