What Combi Boiler Should I buy!!

[hifitrev]

Hello everyone,
I have just joined this forum as I need to have a new boiler fitted, & am seeking advise from all the professional heating engineers on here,
I want to replace my baxi back boiler with a combi, & am not interested in the new baxi back boiler as I want to have a wood burner fitted in its place, I would like to know what boiler should I go for, My 1st choice was the VAILLANT 831 Then WORCESTER 30CDI Now Baxi have just updated the DUO TEC 33KW Now with THINK combustion management system. Plus you can have the Multifit GasSaver fitted between a boiler and flue as an extra, The Multifit GasSaver has been proven to reduce the energy required to produce hot water by 37%. I was also told some time ago that my 22mm copper water flow pipe up to my airing cupboard could be used as my gas feed as its only 1m away from the gas meter & back boiler Down stairs, Advice on this please & what boiler should I go for, I would like one that is not going to give me much trouble & have the best performance and economy.
I look forward to your Reply's PS I live in south wales Pontypridd for anyone near who would like to give me a quote, Thanks Trev.

 

[Solo Heating]

Hi,

I nearly always fit Viessmann Vitodens 100 boilers. I think they're the dog's dodahs and their efficiency is amazing. I used to fit Vaillant but found their heat exchangers started to leak; also have had no end of trouble with some of them since they moved to condensing. Worcester I stay clear of as are just plain crude in my opinion; I've never liked them.

If you install a Viessmann 30 or 35KW combi you won't need a Gas Saver because the efficiency is so high anyway. Viessmann did go through a bad spell with their Vitodens 100 range due to a dodgy park generation system but that has been resolved and I've had practically nil problems in the past 2-3 years. They are very quiet and look neat. If you're gas meter is as close as you say then installing a 35KW model will be OK and you'll be happy with the performance although that will depend on your water flow rate. Oh, and their heat exchangers come with a 10 year guarantee and a 5 year overall guarantee.

Viessmann - Complete solutions for your heating - Oil - Gas - Solar - Wood - Heat pumps

Cheers,

Ben

 

[AWheating]

what is your cold water mains pressure and flow rate?

as reguards boilers its offten a personal opinion, the baxi duotec range are very good imo.

 

[hifitrev]

The water board have just updated the mains, so I will go to screwfix tomorrow and buy a water pressure meter about £12 before the main was updated I filled a 1ltr jug in 5 seconds, if thats any good i'm not sure, Help HelpShift+R improves the quality of this image. Shift+A improves the quality of all images on this page.

 

[AWheating]

so you have 12 ltr per min flow rate which is not great, make sure your stop tap is fully open and repeat the test at different taps to see what you get.

 

[hifitrev]

Hi, I have just made sure that both stop taps are fully open, one in the street and one under the sink, the main tap kitchen sink was the same 1 ltr in 5 seconds, bathroom tap filled to the brim, so just over 1 ltr but will need the meter to look at the water pressure, so if you are saying not great, will I be limited on the type of boiler I can have? I know you can only get out what goes in.

 

[hifitrev]

Hi Ben, I have been looking at Viessmann Vitodens 100 boilers, They do have a good spec, & 10 years on main heat exchanger, Like they say this guarantee isunrivalled in the industry But what about my water pressure as A Wheating in a post has pointed out about 12 Ltr min flow rate not that good

 

[Billy Bob Bob]

go for the older duotec or potterton heatmax

 

[AWheating]

if you only have 12lpm flow rate then that will be the max hot water flow rate also, but likely to be slightly lower due to flow restrictions on a combi boiler. 12lpm is quite fine for most combi boilers but if you have mixer taps or run a cold tap at the same time as the hot then you will likely get 7-8 lpm on the cold tap and the rest on the hot as it will be shared between the two.(best case)

 

[hifitrev]

I have one of those steam showers with mixer taps, so what your saying is 7-8 lpm on cold tap and the rest on the hot is that still ok to have a good power shower
Thanks

 

[Solo Heating]

Hi Ben, I have been looking at Viessmann Vitodens 100 boilers, They do have a good spec, & 10 years on main heat exchanger, Like they say this guarantee isunrivalled in the industry But what about my water pressure as A Wheating in a post has pointed out about 12 Ltr min flow rate not that good

Hi,

I agree that 12 ltrs/min is not great and you could run into problems. I would certainly get an installer to check for you - it might be that all your taps are fitted to pipework which have some sort of restriction, like a ballofix valve, etc.

A simple test is to turn on more than one cold tap (assuming each cold tap is working from the mains and not your cold water tank). Obviously, one open tap will give 12 ltrs/min but what happens with two open? - does the flow of each one drop to a trickle or do they still give close to 12 ltrs/min. If two are OK, how about trying three cold taps, what happens? If three taps turn to a trickle then you'll start to see the problem because when you run a shower it is the equivalent of running two taps so anything else running will create a problem. If someone turns on a third tap and your shower stops then you won't be very happy no matter how good the boiler is.

Cheers,

 

[marleyco]

i mainly fit baxi and fitted 3 of their new neta tec 28. yet to fit the new duo tec. i really like the old boiler and they seem to have improved on them. big bonus for me is they set themselves up to either ng or l.p.g, so if a customer pulls out i can use it elsewhere. turns out the new think range hasnt been energy efficiency approved as of yet, so dont try installing them under a scrappage scheme.

 

[hifitrev]

Thanks to everyone for your help,
I have just tried this, turning the kitchen sink tap on first, then the bath tap, yes the pressure did slow a bit, I then flushed the toilet with the valve on the 15mm copper toilet feed pipe fully open, I then got just half a ltr in 6 seconds with 3 taps open, Do you think this is ok, or will I just have to put the dish washer on at night & the washing machine, so then this should not effect the flow in the morning when having a shower.

Cheers

 

[Solo Heating]

Thanks to everyone for your help,
I have just tried this, turning the kitchen sink tap on first, then the bath tap, yes the pressure did slow a bit, I then flushed the toilet with the valve on the 15mm copper toilet feed pipe fully open, I then got just half a ltr in 6 seconds with 3 taps open, Do you think this is ok, or will I just have to put the dish washer on at night & the washing machine, so then this should not effect the flow in the morning when having a shower.

Cheers

I would say that is acceptable for a combi to work for you if you are indeed getting half a litre in 6 seconds with multiple outlets running. It does depend on how many occupants you have in your house. If it's just you then it won't be a problem. If there are lots of people all requiring hot water first thing in the morning then it could be a major issue. A bath will take much longer to fill for example.

What it does mean is that you don't need to go for a combi which can give 20litres/min of hot water since it'll be partially redundant. A cheaper one which can cope with 10-12 litres/min will be just fine. You will need further advice of course.

Cheers,

 

[asdheating]

I mostly prefer Vaillant (unless the customer needs something specific). None of the 824s and 831s (ecoTEC pluss) that I installed gave me any trouble.

 

[hifitrev]

Well I was always looking at the Vaillant 831 ecoTEC Plus, does any one on here know anything about the Vaillant ecoTEC plus 937 requires no hot water cylinder or cold water storage tank in the loft. The ecoTEC plus 937 provides a high level of hot water comfort due to its 'actoSTOR' fully integrated storage Tank
Now they say it will work on low water pressure of (0.75 bar) so I need to get this tested & get a water pressure meter from screwfix Does my 12 ltrs / a min Equate to (0.75 bar, I also have a solid london brick wall for this boiler to bolt to, as people are right it does look like a fridge on the wall

Cheers

 

[Solo Heating]

Well I was always looking at the Vaillant 831 ecoTEC Plus, does any one on here know anything about the Vaillant ecoTEC plus 937 requires no hot water cylinder or cold water storage tank in the loft. The ecoTEC plus 937 provides a high level of hot water comfort due to its 'actoSTOR' fully integrated storage Tank
Now they say it will work on low water pressure of (0.75 bar) so I need to get this tested & get a water pressure meter from screwfix Does my 12 ltrs / a min Equate to (0.75 bar, I also have a solid london brick wall for this boiler to bolt to, as people are right it does look like a fridge on the wall

Cheers

The 937 model is a boiler with integrated hot water store (as you describe) which makes it a storage combi and storage combis or more commonly used where the hot water use is high. It can help to overcome any problems with poor flow/pressure because the store is pressurised and therefore adds a little bit of pressure to the hot water system. Again, it depends on the demands you think there'll be on the hot water in your house because there's no point in spending the extra money on that boiler, and taking more space than necessary, if a standard 26KW combi will do the job.

Water pressure and flow rate are not linked in the way people think they are. A gravity system with a pressure of 0.5 bar can give 20-30 litres/min at a bath tap (because the pipe work is much bigger to compensate), yet a pressurised system working at 3 bar can give only a few litres/min (because there is a restriction or the pipe sizing is too small or multiple taps are running). Your water provider is meant to ensure you get at least 1 bar into the house but that's not always the case so never assume that. A proper test will be required.

 

[hifitrev]

Hi, I have just done a water pressure test at the kitchen sink, by removing my cold feed to the dishwasher, I had a reading of 3.5 bar, I then went and turned the cold bath tap on and the reading dropped to 2 bar, I then went on to do a 9 litre bucket flow test.

It Took 49.17 seconds to fill my 9 Litre Bucket
Flow Rate 10.982306284319707 Litres/pm
80% is usable 8.785845027455766 Litres/pm

Is this any good, and will I still be ok to Have a combi Boiler

You Can find the calculator Here [DLMURL="http://aquatrad.com.au/the-bucket-flow-test"]The Bucket Flow Test ::: Aquatrad/Water Pros Dandenong For The Best In Pumps & Irrigation[/DLMURL]
Cheers

 

[cdodds2004]

go for a worcester bosch 30si and get it fitted by a worcester acredited engineer! full 7 year warranty from worcester, need i say more, a few other good boilers available but 7 yr full warranty speaks for itself!

 

[Chrisgy]

go for a worcester bosch 30si and get it fitted by a worcester acredited engineer! full 7 year warranty from worcester, need i say more, a few other good boilers available but 7 yr full warranty speaks for itself!

Is that on all Worcesters? Just done a baxi course they give a 5 year warranty on their new boilers do you know who to contact to get on the Worcester course?

 

[Destroyer2813]

Saw somthing the other day on the si"s and another model five year warrentys till the end of the year free of charge to normal instalers. You have to be Worcester acredited to give 7year Chrisgy and for that u have to fit so many of there boilers a year. You can do training courses with Worcester 50quid a course

 

[Chrisgy]

I saw a leaflet today it said an extra year til the end of October. Thought it was just a training course to get accredited thanks anyway

 

[Tellitacitis]

Go for either the Worcester or the Vaillant. We fit 500+ boilers and had too many problems with Viessmann. Worcester spend a fortune on PR/Advertising hence the higher price for no clear advantage. If you run into a problem (which we did) with Viessmann you really have got a problem, guarantees or not and it can get sticky if you try and prove anything - trust me! The other problem with Viessmann is that they adopted the 'flat bashing' route to try and compete in the volume market place (failed and the wrong route IMO) and as an individual you're very much the poor relation. Personally I'd opt for Vaillant and if you find a supplier on their 'cash back' incentive you might get an even better deal. They were also offering a 6 year warranty but I believe that's just finished, so it's now 5. I think Vaillant have got an extended warranty on the heat exchanger but we've never had a problem. Viessmann had the potential of a good product but let themselves down with too many niggles and poor after sales service.

 

[Solo Heating]

Go for either the Worcester or the Vaillant. We fit 500+ boilers and had too many problems with Viessmann. Worcester spend a fortune on PR/Advertising hence the higher price for no clear advantage. If you run into a problem (which we did) with Viessmann you really have got a problem, guarantees or not and it can get sticky if you try and prove anything - trust me! The other problem with Viessmann is that they adopted the 'flat bashing' route to try and compete in the volume market place (failed and the wrong route IMO) and as an individual you're very much the poor relation. Personally I'd opt for Vaillant and if you find a supplier on their 'cash back' incentive you might get an even better deal. They were also offering a 6 year warranty but I believe that's just finished, so it's now 5. I think Vaillant have got an extended warranty on the heat exchanger but we've never had a problem. Viessmann had the potential of a good product but let themselves down with too many niggles and poor after sales service.

That is true. I still fit Viessmann and only Viessmann but they did go through a very bad patch 4 years ago because their early model of the Vitodens 100 range had a fault which nearly all boilers suffered from. I was actually given a contract to change the problem part (plus repair any other faults) in dozens and dozens of flats in Swindon, Bristol and Bath. But actually, because Viessmann boilers are so easy to work on, it took seconds to do the work. Very very rarely was the boiler breakdown due to anything else and all the new boilers I've fitted have been almost fault free.

Now compare that with Vaillant whose modern heat exchangers rot after a few years and to me there's just no comparison. Another plumber I know has had so many problems due to rotting that he's recently switched from Vaillant after years of using them. I personally went through a problem with a number of Vaillants which due to a factory error were made with no heat exchanger seal and Vaillant refused to acknowledge the error until a rep let it slip that they knew about it.

As for Worcetster, their manufacturer and design is just clumsy in my opinion but I appreciate that they are very popular and do the job.

I guess it shows that no manufacturer is perfect and all will have times when things are good and when things are bad. It also shows that we all have personal reasons for choosing a boiler. At least I can get in touch with Viessmann almost instantly unlike Worcester and Vaillant where I have to wait for hours to be served only to find myself speaking to someone who doesn't know anything. There's just no beating Viessmann's technical department; what they don't know isn't worth knowing.

 

[Tellitacitis]

We have never had a problem with Vaillant heat exchangers yet - they are all s/s although we all know that can vary especially with the Chinese rubbish. I do know that Viessmann manufacture their own and in that area it is probably as good as anybodys. There were actually two inherent faults with the Viessmann products. We also found them slow to react due to lack of engineers when there was a problem and the delays simply went on an exponential curve becoming unacceptable from a customer's point of view. In fact we are still having to replace some installs gratis as Viessmann put up so many obstacles once we opted for other manufacturers and as a result we will never deal with them again. It sounds like you're on an 'approved repairer/installer' deal and hence the brand loyalty. We on the other hand, as said, fit 500 + boilers annually and fit that which we consider the best solution in the situation - we do fit Worcester when confronted with certain flueing issues as they are the only choice - we don't have any brand connection whatsoever. Buy Viessmann and you're tied in to a low volume (in the UK) product and all that can arise from that. On the other hand every engineer out there knows Vaillant/Worcester. Given a choice our 40 + engineers will always opt for either of the big two with Vaillant being the easier install.
You obviously got through to the right tech person but every company has its experts and its idiots, Viessmann included.
Customers aren't interested in excuses from manufacturers (maybe they're more polite in the West Country) but in London they won't wear it and if they've got a problem we've got a problem, which we can do without. 'Goodnight Vie...(...)'

That is true. I still fit Viessmann and only Viessmann but they did go through a very bad patch 4 years ago because their early model of the Vitodens 100 range had a fault which nearly all boilers suffered from. I was actually given a contract to change the problem part (plus repair any other faults) in dozens and dozens of flats in Swindon, Bristol and Bath. But actually, because Viessmann boilers are so easy to work on, it took seconds to do the work. Very very rarely was the boiler breakdown due to anything else and all the new boilers I've fitted have been almost fault free.

Now compare that with Vaillant whose modern heat exchangers rot after a few years and to me there's just no comparison. Another plumber I know has had so many problems due to rotting that he's recently switched from Vaillant after years of using them. I personally went through a problem with a number of Vaillants which due to a factory error were made with no heat exchanger seal and Vaillant refused to acknowledge the error until a rep let it slip that they knew about it.

As for Worcetster, their manufacturer and design is just clumsy in my opinion but I appreciate that they are very popular and do the job.

I guess it shows that no manufacturer is perfect and all will have times when things are good and when things are bad. It also shows that we all have personal reasons for choosing a boiler. At least I can get in touch with Viessmann almost instantly unlike Worcester and Vaillant where I have to wait for hours to be served only to find myself speaking to someone who doesn't know anything. There's just no beating Viessmann's technical department; what they don't know isn't worth knowing.