Advice on new boiler

[DistortedVision]

I've asked on another forum but I'm going to ask here as well. We have a 16 year old Glo-worm Hideaway 28kW regular boiler with hot water cylinder, cold water cistern and header tank.

I preferred to have a combi boiler and this is what nearly every installer had recommended. I was going to go for a Worcester Bosch 440CDi Highflow and the best quote I've received is £3400 cash from an approved WB installer and hence comes with a 6 year warranty. The installers on the Ultimatehandyman forum said that is ridiculous. Most said I should get a system boiler and a 200 litre unvented hot water cylinder instead. We have two bathrooms (one main and one ensuite). Only the main has a bath in it but its never used. Both have electrical showers but a thermostatic mixer valve shower is going to be installed in the main bathroom when its renovated next year. Its a 5 bedroom house but there are only 3 people living here. They are 12 radiators in total. My main concern is the DHW flow rate. The professionals on the other forum have said that the flow rate on the Highflow models is poor after the 60 litre heatbank has been depleted. Also they said the build quality of WB is poor in general. The consensus viewpoint on there was that if I should go for a combi I should get a Valiant 837. Personally for cosmetic reasons I would prefer to get a floor mounted rather than a wall hung one but its not critical.

I have been looking at non mass market boiler manufacturers like Veissmann. I had an approved installer come round yesterday and he in fact said Worcester Bosch, Valiant and Veissmann were all good and of equal quality. I was looking at the Veissmann 222-F as it has a large 130 litre heatbank. But the installer said we neither had the DHW requirements to justify installing one nor the plumbing infrastructure. All the pipework in our house is 15mm and he said it would need to be upgraded to 22mm to achieve its full performance. I admire him for his honesty.

Here is the breakdown of the Worcester Bosch Quote:

1. Add Cleanser to the central heating system prior to works commencing.
2. Drain down and remove the existing Glow-worm Hideaway central heating boiler.
3. Drain down and remove the existing hot water cylinder, cold-water tank and header tank.
4. Supply and install a Worcester 440 Cdi condensing combination boiler above the existing boiler position.
5. Run a new 28mm and 22mm gas supply from the garage in the exisiting boxing to the new central heating boiler.
6. Supply and install a TD 200 plug in programmer.
7. Supply and install a TD 10 room thermostat.
8. Supply and install all pipe-work and wiring.
9. Brick up the existing flue.
10. Tile the floor area beneath the existing boiler position to allow the new jig to be fitted.
11. Supply and install new chipboard to the area beneath the existing tank positions in the loft area.
12. Fill, test and commission the central heating.
13. Add inhibitor to the central heating.

My personal preference is a combi over a system boiler. I'm really sick of it all, I'm completely undecided. We've had 10 quotations now. Any advice would be greatly appreciated.

Many thanks!

 

[ecowarm]

System boiler and unvented if main flow rate and pressure acceptable. Get the boiler sized correctly for house and old system will need power flushing probably.

 

[DistortedVision]

Everyone on the other forum said the same thing. But every plumber I've asked for quote advised against it citing the cost would make it prohibitively expensive.

 

[ecowarm]

That's rubbish a system boiler and unvented cylinder or thermal store is not going to cost much different, ok you may have to upgrade the water main but you may be able to fit a 12kw system boiler so you dont have to upgrade the gas for a 30kw+ boiler and it will be a lot more economic

 

[DistortedVision]

ecowarm can you please clarify something I'm confused on. Doesn't a system boiler with unvented cylinder cost significantly more to run. The boiler is switched on/off to maintain the water in the cylinder at a constant temperature. It seems wasteful to me. Or am I missing the point?

 

[ecowarm]

have the time control set to say 1 hour in the morning and 1 in the evening, or if no one home during the day, just an hour or two at 5pm so the boiler get one long run to heat it rather than cycling through the day.

 

[DistortedVision]

Had a Viessman approved installer visit this evening. He recommended the Vitodens 222-F combi which has a 130 litre heatbank or a system boiler with UV hot water cylinder. Hes the only plumber that visited that doesn't think a regular 35kW combi would suffice. I'm inclined to agree with him.

What do you all think of Veissmann?

 

[ecowarm]

Excellent

 

[GQuigley67]

i would say if the price is right then go for it, what system boiler is he offering ?

 

[doitmyself]

Has anyone bothered to check your incoming cold water flow rate?

 

[DistortedVision]

Yes a couple of the installers that visited to give a quote checked it with a flow cup at the outside tap and the kitchen sink. Its 18 litres/min.

 

[doitmyself]

Yes a couple of the installers that visited to give a quote checked it with a flow cup at the outside tap and the kitchen sink. Its 18 litres/min.

That'd fine if you only running one bath or having one shower. But if you have one two people showering at the same time the flow rate may not be good enough.

Did the installers also measure the dynamic pressure?

Many unvented cylinder manufacturers recommend a minimum flow rate of 20 litre/min at a pressure of 1 bar.

Don't forget that with a combi or unvented system all water is supplied directly from the incoming cold main. There is no storage tank to feed the toilets, washing machine, dishwasher, hand basin etc. So, if someone decides to wash the car while you are having a shower, you will notice a reduction in flow.

 

[DistortedVision]

I'm not sure if that installer was reputable and honest even though he was an approved Viessmann installer. The first approved Viessmann installer told me that we did not have the requirements to justify the 222-F. He also said we had 15mm pipes and that the pipework would need to be upgraded to 22mm to allow the boiler to perform as designed. This would include upgrading the mains pipe to 22mm from 15mm and he said this would be prohibitively expensive. He recommended any 35kW combi and said the DHW flow rates would meet my requirements. This is where I was uncertain. From from my understanding once the heatbank has been depleted on models like the Worcester Bosch 440/550Cdi Highflows the DHW flow rate drops considerably?

The second installer recommended the 222-F without reservation. I got the impression he may have just been trying to sell a more expensive product with more work to make more money.

 

[DistortedVision]

No the installers didn't check the dynamic pressure. I was concerned about that doitmyself. I have another installer visiting this afternoon I'll ask him to measure the dynamic pressure. Lets say the flow rate is below 20litres/min then what can be done?

Sorry I've had over 10 quotes now. I'm still undecided. I prefer a combi and thought the 222-F might be a good solution with its large 130 litre heatbank. Its expensive and I want to make sure I've made the correct decision.

Others have recommended the Valiant 837 but I'm not personally convinced its the right boiler for us.

 

[That Extra Mile]

No decent plumber would recommend a mains-supplied system (combi of unvented cylinder) without measuring flow rate and dynamic pressure. You should immediately disregard all those who didn't make these checks.

 

[DistortedVision]

Is there a cheap tool I can purchase to test the dynamic pressure myself?

 

[Mrs Tara Plumbi]

omg 10 + quotes!
This should be enough for you to make a decision.
I don't wish to be rude but are you causing confusion?

i may have this wrong but I think you said you would prefer a combi because the people in your house have low hot water demands even though you live in a big house.

Perhaps you said this to the heating engineers so they have quoted for combis at your request.
Hardly surprising they suggest WB as WB is the post common installed combi
And who wouldn't want a 6 year labour and parts warranty
And WB have good aftersales back up/ technical support.

But there are plenty of other good combis that could do this job.
I wouldn't get hung up about the stored water thing IF only one person is going to drawing hot water at a time from the combi eg for a shower you do not need the high flow rates given by storage combi. and you do not need to worry about the storage water running out, although I seem to remember it refills back up to temperature reallly quick if that is what you want.

IF your incoming water pressure is high enough a combi will be fine - I have one in my house and I have lived with combis in other house too. There are 5 people living in my house 2 adults 3 kids.

Having said that - all those qualified heating engineers who are telling you NOT to get a combi are giving you the benefit of their knowledge - generally most of the time a combi is NOT right for a big house with multiple bathrooms. But it is your house and you know how you use your hot water.

My recommendation to any one looking for new boiler/ heating installation - the most important thing is to find a really good installer. Who is the most professional? Got experience and will give you good advice? Will still be around in business in years to come to service your boiler and help sort out problems?
AND remember that for your warranty to be valid you must have the boiler serviced within 12 months and every 12 months from date of installation.
And the boiler must be correctly installed.

Don't go with the cheapest

 

[DistortedVision]

You may be right - I may be causing the confusion.

But of the 10 plumbers that have visited - there were only 2 that I would actually trust to do the work. You're absolutely right not to go with the cheapest. I should point out that not all those that visited have actually sent me quotes either.

I'm waiting to see how much the Viessmann 222F is but I have a feeling its going to be prohibitively expensive. If it is I think we will go for the WB 440CDi Highflow.

 

[That Extra Mile]

Is there a cheap tool I can purchase to test the dynamic pressure myself?

Any plumbers merchant will sell you a gauge with washing machine type fitting. Connect it, turn on the valve and note the pressure. Then turn on a tap and note the pressure again - this is the working or dynamic pressure. Both the washing machine connection and tap must be on the mains supply! You really shouldn't be having to do this though!

 

[arran197]

I suppose it depends how much you REALLY use the hot water. Normal combi's aren't very good for mixer showers, especially in the summer. But I think if you do go for one which has a small water storage, it might be ideal for you. By the time you have used the water you will probably be out the mixer shower anyway! I went to a 440 (the scale reducer was leaking on the incoming cold) that was serving about 6 flats in a communal building and they had no problems.

 

[DistortedVision]

We had one of the Worcester Bosch approved installers come back today. He said actually a system boiler plus unvented hot water cylinder might better suit us. He's going to quote us for a 210 litre UV hot water cylinder plus a WB system boiler. He said the quote might actually be a little cheaper.

I think I might go for a Viessmann Vitodens system boiler and UV cylinder. I've just yet to find an approved Viessmann installer that I liked.

 

[GQuigley67]

very picky arent we lol

 

[DistortedVision]

Very....I'm like this about most things. I just had feeling that I was going to be disappointed with a combi. Only one of the Viessmann installers seemed competent and trustworthy. Two of the Worcester Bosch installers I liked.

Sorry I've lots of bad experiences with cowboy plumbers.

 

[ecowarm]

Very....I'm like this about most things. I just had feeling that I was going to be disappointed with a combi. Only one of the Viessmann installers seemed competent and trustworthy. Two of the Worcester Bosch installers I liked.

Sorry I've lots of bad experiences with cowboy plumbers.

Why not stick with the viessmann guy? he should be able to advise on all types of boilers and systems

 

[GQuigley67]

we can install any boiler you like, well most people can. If you specify a certain boiler the guy will be happy to install it and it will be installed properly, they are all the same, and end of the day he will be getting payed for it so he'll do it.