Buderus Combi Specification

[Fumf]

I'm about to specify a combi for a new install, which will be fully zoned with motorised valves.

Buderus was favourite, till I tried to find out whether it has any short cycling prevention (since it will sometimes be running with just a few hundred Btu/h of load). I can't find anything on their web site, or in the installation instructions, and the technical help bloke at Buderus hadn't a clue what I was on about.

Can anyone tell me from their experience of these boilers, please? (500 or 600 28C)

If they haven't, I'm inclining towards either Vokera Linea HE or W-B 30Si, since I'm not over-keen on what I've read about Gianoni stainless-steel heat exchangers. I do like the detail in the Vokera installation instructions, and the fact that they modulate down well, which the W-B doesn't.

 

[Gasguru]

Have a look through the 500 service manual - there's reference to a 5 minute overun before re-ignition.

 

[bengasman]

I installed a couple a few years ago, never had a complaint about them. great design, super easy to work on, you can strip them completely in about half an hour. Downsides: no name recognition with the public and a bit noisy. Come standard with integrated wireless roomstat. If I was told correctly, originally an well established Dutch company bought by bosch

 

[Paul Barker]

The 600 range is the best for you as it is extra quiet. Fit the 600-28c with a dedicated radiostat and it modulates the burner from room temperature, so instead of starting and stopping it just trickles happily all day vertually silently. The pump is modulated at the same time.

the 500 range is more convensional with fixed head pump, less effective soundproofing, though I don't see that as an issue.

Both boilers (500 and 600) are of the highest quality and most impressive consideration of the engineers needs available in the world.

The helpline is manned by worcester staff whose jobs rely on worcester beating buderus in the fight to sell boilers for Bosch BBT in the UK. Sooner or later Worcester as a company will have to come up to Buderus's standard or jobs will be affected.

They aren't helping themselves by not aquainting themselves with specific knowledge of the Buderus. I as an engineer have found the knowledge of worcester helpline staff about the Buderus I could teach my 10 year old.

 

[giblets]

If I was told correctly, originally an well established Dutch company bought by bosch

As I understand it, Buderus & W-B are both owned by BBT Techknowlegies(?)

Excellent bit of kit both the 500 & 600. Only install these now.

Have to agree about the Help Line - bloody awful. Also availabilty of accessories can be a bit thin on the ground.

Some of the larger output units (i.e. the 800 series) are well worth a look if anyone needs a steamer in place of a Keston.

 

[D_Hailsham]

As I understand it, Buderus & W-B are both owned by BBT Techknowlegies(?)

From the Bosch website:

BBT Thermotechnology GmbH is the heating and hot water division of the Bosch Group with a turnover of over 2.5 billion euros and the largest supplier of heating products in Europe. BBT Thermotechnology UK Ltd (the UK division) has two successful and growing brands - Worcester and Buderus which provide high quality, highly efficient and durable heating solutions to the UK.

 

[giblets]

I stand corrected.

 

[simond]

The Buderus 600 series is the one to go for, the 500 is a cost reduced model for the UK market (you should know what that means).

We have had issues with the condense siphons (they are just fitted for the UK market) also the warranties are kept shorter than Worcester, by Worcester in the UK. I am sure you can reason why, they don't want their larger cousin adversely influencing their own sales.

If you fit a Buderus boiler you get a 2yr warranty, and the customer can elect to pay a further £90-110 to extend the warranty to 5 yrs with an insurance company. They have to pay for the repair and a £15 admin charge, the repair cost (exc £15) then has to be claimed back from the insurers.

Can'd be bothered with explaining this to customers (we get 5yrs no quibbles from our other boiler suppliers), we don't want to offer 'insurance' just want proper repairs.........and still waiting for replacement condense parts so no more Buderuses will be fitted by my company.

 

[Fumf]

Thank you very much for the advice, gentlemen.

The Service information for the 500 (but not the 600) does indeed have an excellent explanation of the boiler's operating logic. As I understand it, the pump over-run does not, however, affect whether it can short cycle. If the room stat calls again for heat after the 10s fan purge but during the over-run period, then as far as I can tell the start-up sequence begins again. If the room stats are still calling for heat, but the set flow temperature has been reached because the boiler can't modulate down far enough, the interval before it fires again is governed by how long it takes for the flow temperature to drop to 6 deg below its setting. The 6 deg is adjustable, so it might be worth setting it to say 15 degrees below.

Because I'm proposing five separate zones, each with an MV, and a call for heat when any of the auxiliary contacts makes, I'm just a bit concerned that this will lead to short cycling. I suppose the other way of looking at it is that on a cold day there's a good chance there'll always be at least one zone calling for heat.

I can't see how to use modulating room stats with multiple zones. Have I missed something?

Noise isn't a big consideration, so are there any other factors that should push me to the cough up the extra £150 (£752 as against £898) for the 600? I can't find any reference to how the 600 modulates its pump.

The comments on the engineering quality are much appreciated: I like real engineering.

Kevin

 

[bengasman]

The comments on the engineering quality are much appreciated: I like real engineering.

Kevin

in that case, sign up for a couse with buderus or ask if they still have reps doing demos in your area.
That is the way I got impressed with them. went to my supplier one day and there was the rep. “Can I show you something about our products?” I appreciate they have to do a job, but as I was in a rush (as always) I politely brushed him off. By the time I had my bad with goodies, he had stripped the boiler to bits. Completely.
I promise you that stunt will thoroughly grab the attention of anyone who earns money servicing or repairing boilers.

 

[snes]

As a consumer, I was converted to the Buderus cause by Paul Barker - but then got waylaid by Dan Robinson and the minimalist charms of the Atmos boiler.

Both are Dutch boilers, both seem very well engineered, but the sheer simplicity of the Atmos combi is compelling.

But I am not a Corgi - so people who have experience of these boilers may have a different opinion of their merits, especially working on them.
Any views, or are they simply two very good boilers?

 

[Agile]

There are so few installed in the UK that independents are unable to reach any viewpoint about them!

All you will get is an installers view based on installing a few.

The Worcester Juniors semed very reliable at first but now that the first ones are two years old we are getting quite a few failures.

The Vailliant 824s were fine for about two years and then the diverter valves all started failing.

Tony