Converting from Conventional to Combi

[Jurassicspark]

Do you know what sort of pipework you have -is it conventional 22mm ring with 15mm going to radiators, or is it microbore?

Also is the current gas pipe feeding the boiler in 15mm or 22?

 

[clayton]

Do you have a system filter that you can add inhibitor via.

 

[Madrab]

We have a conventional system with tanks in the loft. The bathroom toilet flushes with water from the cold water tank in loft. What would happen if we convert to a sealed system? How would water get in the toilet?

Converting from and open vent (OV) to a sealed system only changes the way the CH system operates so as far as that is concerned nothing - The 2 systems are independent of each other. The small cistern in the attic feeds the CH system, the large one feeds the toilet. You can go to a sealed system without removing the large cistern - which may also be feeding your HW cylinder if you have one.
If you are talking about converting from an gravity fed cold water to mains water then that's a different story

We currently get a lot of air in our radiators daily which I think is to do with the set up in the loft and sludge. Hoping no underground leak. If there was an underground leak I know a combi would lose pressure overnight. Would a conventional boiler loose pressure too? We never have a problem with our boiler.

The CH system needs properly serviced and then correctly maintained. Someone with experience of open vented CH systems should be able to sort it out but depending on how long it has been left will determine how much time and funds it will need to return it to proper working order.

Alternatively you can go to seal the CH system which will allow the small cistern in the attic to be removed but that won't sort out the sludge issue and if there is a leak on the system somewhere then a sealed system can stop working when the boiler pressure drops below a certain level - some boilers can keep working. The caveat to this is that your current boiler may not be able to be converted to a sealed system.

As far as changing to a combi is concerned, how many bathrooms/showers/HW outlets would be used @ once. 95% of combis can only feed one hot water outlet at a time properly, without incorporating really clever water saving outlets and careful usage management.

 

[debbiea]

the annual service is only the boiler not the system

old systems get sludge build up and once you get air in the system is accelerates corrosion

Really you need to sort out the system issues -radiators and pipework, whether you have a system boiler or a combi

Do you know what sort of pipework you have -is it conventional 22mm ring with 15mm going to radiators, or is it microbore?

22mm. We have no issues with hot water. The hw cylinder heats up pretty quickly

 

[debbiea]

Do you have a system filter that you can add inhibitor via.

No

 

[debbiea]

Also is the current gas pipe feeding the boiler in 15mm or 22?

22

 

[Jurassicspark]

22

Okay, so I reckon the boiler you have currently is a condensing one. What is the model of the current boiler? If I was you I would rectify the problems you are facing right now (an easy job for an average DIYer) and keep the existing system till it breaks down.

 

[debbiea]

Okay, so I reckon the boiler you have currently is a condensing one. What is the model of the current boiler? If I was you I would rectify the problems you are facing right now (an easy job for an average DIYer) and keep the existing system till it breaks down.

Worcester Greenstar RI. Yes condensing

 

[Jurassicspark]

Worcester Greenstar RI. Yes condensing

I don't see a real reason for you to convert to a combi unless you want to make space, e.g., for a loft conversion. If I was you I would drain down, flush the heating system, check places for leaks e.g., radiator valves and then add a suitable inhibitor.

 

[Madrab]

As far as changing to a combi is concerned, how many bathrooms/showers/HW outlets would be used @ once.

???

 

[debbiea]

???

Two bathrooms and a downstairs toilet

 

[clayton]

You don't need a new boiler, just fix the overflow from the F&E tank in the loft, put some inhibitor in the system once done maybe fit filter.

 

[Madrab]

Two bathrooms and a downstairs toilet

Avoid a combi, it just won't deal with more than one HW outlet at a time comfortably.

something to do with the tanks in the loft as when there is a lot of air it leaks outside

I wouldn't suggest it's leaks outside, rather the system has leaks (only outside leak there would be is if the attic cistern was overflowing and it was running from the attic overflow). Air in the system could also be pumping over, as the system is restricted by corrosion build up and that can introduce air bubbles into the system too. If you are able to get a magnet to stick onto the pipework at the feed and vent then yes the system will have corrosion build up and that can be fixed by either an aggressive cleaner run through it or the section replaced.

All in all not that difficult, for an experience resource, the trouble it sounds like though, is getting that resource.

 

[debbiea]

Thanks everyone.