are system boilers any good?


Postby missperplexed » Wed Jul 09, 2008 6:19 pm

Hi after having a succession of gch engineers through my home for quotes,the lastest one has suggested that the pipes (about40yr old) may not be strong enough for a combi and could have leaks. it would be at my own risk. this has almost caused me to go into major shock! alternative is a system boiler. what's everyone opinion on installing one of these versus the cost and major major upheaval of having new pipes installed for a combi will entail. after having loads of work done in the house over the last year, not sure I can face much more (I know I should have done this first but Im daft and now short on cash only changing system cos I cannot stand the fire that comes with it)

hope you can help :? :D [/b]
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Postby htg engineer » Thu Jul 10, 2008 2:22 pm

It's not the fact that it's a Combi boiler that is the problem. The problem is the age of the pipework and what a pressurised system could do, pressurising old pipes can cause leaks.

So it doesn't matter if you go for a combi, or a system boiler if it's a sealed/pressurised system the pipework might not be up to the job.

Get a price for an open vented installation, and then a price for a combi with new pipework. If you need new cylinders etc - there wont be much difference in price.


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Postby missperplexed » Thu Jul 10, 2008 8:58 pm

pardon my ignorance but whats an open vented system? also are these approved in the HIP's packs? I've been quoted for a new combi and new pipes and it wasnt too bad,its having the whole of the house ripped apart including laminate flooring in many rooms thats my concern. Im looking for the best way to avoid having to do that but also meet current gov regs

thanks for your reply
missperplexed
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Postby htg engineer » Sat Jul 12, 2008 4:09 pm

If you can I would go for a pressurised Condensing Combination Boiler system. This removes the need for tanks and reduces the amount of pipework required.

Open vented means the system is not pressurised - not filled from cold mains. The heating system fills via a tank in the loft. A pressurised system has a pressure relief valve. A open vented system has an open vent for the safe discharge of excess heat/water.

The down sides of an open veanted system are:
More pipework
Storage tanks, take up room/storage space. Can freeze if not protected.
Ball valves require changing
Airlocks, if you drain the system. it can take hours even days to sort problems out
Blocked cold feeds (over years)

If the upheaval of each room is too much, you have 2 choices:

1) fit a new combi boiler leave the old pipework, fit TRV's to radiators pressurise and and see what happens, . It may be ok, the pipework may be sound. I have seen installations like this that have no or very few problems.

2) fit a system boiler, this will require new cylinder etc etc. I imagine with your system pipework being 40 yrs old - your current system will not fully pumped so there will be pipes that will have to be altered and some will not be re-used.

While still comforming to regulations, open vented systems are not advised, and very rarely installed. The sealed system (pressurised) is the modern system and if installed properly will give less problems.

hope this helps

htg
htg engineer
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Postby missperplexed » Wed Jul 23, 2008 9:49 pm

many thanks for your reply. I have had about 7 plumbers give me quotes over the last few months, and only one has mentioned there may be a problem with the old pipes. so...I think I am going to leave them and just decide whether to go for a combi or a system. getting nearer to a decision...:)

oh..another question. can gas be run through old water pipes..thats what some of the plumbers have talked about doing. its very confusing when they contradict each other
missperplexed
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Joined: Wed Jul 09, 2008 6:04 pm


Postby htg engineer » Thu Jul 24, 2008 6:51 am

Gas pipes cannot have compression fittings underfloors, in walls or anywhere that is not accessible. So if they decide to use this pipe they're going to have to check the entire length of the pipe. So if going to the hassle of lifting floorboards etc etc why not renew ? (probably because they're not planning to check the pipe, just carry out a tightness test to check it's sound).

Even though you can get water entering gas supllies, re-using a water pipe for gas is not ideal. Unless it's a vertical pipe you will never get all of the water out by draining it.

So this excess water is going to end up in the gas valve, if the old primaries or heating pipes - it's probably going to be black water - could cause more problems to parts of the new boiler.

htg
htg engineer
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