Viessman vitodens wb1a heat exchanger -installer wanted

[Beardie]

I have a vitodens 100 wb1a that was I installed in 2005. The boiler started short cycling earlier this year , temperature rising in 2-3 degrees and then shutting down early before cycling again. The engineer added 2 bottles of x800 and it seemed to fix the problem for about 2 weeks. Now it's worse than before and the suggestion is that the heat exchanger is blocked.
Apart from minor parts like electrode and igniter the boiler has been good and ideally I would want another but need to ensure that I find an installer that will fit or fix the boiler properly. I don't recall the installer ever putting any flush or cleanser in when the boiler was fitted other than x100 inhibitor.

My options appear to be get a heat exchanger replaced or a new boiler.
The viessman engineer will call me back later next week with a price for both but recommended a Worcester Bosch boiler! Very strange...I have no experience or recommendation for these so am a little apprehensive. I would rather have another viessman if fitted properly, flushed etc...

So opinions and suggestions please on any fitters in the telford, Shropshire area that I can trust to do a proper job...many thanks

 

[Agile]

I would expect that your blocked heat exchanger could be cleaned.

But that needs an engineer who knows how to do that and what chemicals to use.

I seem to be one of the very few who will actually do the messy work of cleaning these.

Amusingly you live in the hole of Viessmann boilers in the UK.

Tony

 

[Tibbot]

The Viessmann heat exchanger is a one piece continuous coil, so no reason why it can't be powerflushed.

 

[Beardie]

Thanks Tony,
yes viessman are here in town and the engineer who is coming back to me is one I have taken from there own list on the website.
It just concerned me he was recommending a Worcester as a replacement...if you know of anyone that would clear out the system, that's all I ask for..!

Bit dubious about some power flush bods unless I can get a recommendation...

 

[Agile]

He will be an approved installer, basically someone who is gas reg and has been on their training course.

He may prefer Worcester boilers or he may be on the Worcester list and required to fit a certain number of their boilers to stay on their list.

In my view your boiler IS repairable, but few engineers will do it.

Interestingly, Viessmann is one of the few boilers which can be cleaned in this way because the HEs are a single loop of tube.

The others have several loops in parallel and if any become blocked they cannot be cleaned.

Tony

 

[holty]

the heat ex on these are one of the best around. very easy to clean. probably doubt its the heat ex thats blocked. but more likely the rubbers hoses. dont get me started on these. for the price around ten to fifteen pound each. id replace and look at the whole system. also if not flushed correctly x800 can cause problems. the wb1a was ****, compared to the wb1b/c but id still say its better than a worcester ****e. p.s feel the rubber hose and i bet its crunchy.

 

[Beardie]

Thanks holty.
I will mention the option to clean the Hex to the engineer when he calls back. The rubber hose, is this the one for the condensate , or something else?
Btw, what method us used to clean the hex, is it as straight forward as the power flush...as I will then need to establish if he does this, or are all engineers trained and capable.

Regards

 

[CombustionGuy]

Just a note nobody on Worcester list has to sell boilers.... I'm on "Worcester list" and i fit what I think is best for the job and customer. I think a mightygash should be installed as that would be fine on a dirty system ( they can run on treacle intergas tried it)

Also I'm not saying that you shouldn't clean the system, you should also most people can flush the boiler properly. It's not rocket science. But like holty said the rubber hoses are known for being a arse on these just like the valliants and glowworms

 

[JohnD]

Because of the orientation of the coil, it is possible for air to collect at the top of the loops. I sometimes get that in summer (have an Alpha pump) which obstructs flow.

On mine I can blow it out by turning the pump to manual max speed for a day.

Might be worth a try. My system is very clean.

You don't recall your system being cleaned so perhaps it isn't.

I am a DIYer.

 

[Beardie]

Thanks johnd
My pump has a plug in connector and therefore I don't fancy messing with trying to run it manually. It's a variable Flomaster, and I know when it's set to max on the linear setting, it sort if runs at high then low speed then high in a pattern, which makes me think there is a restriction (blockage). When set at max on the non linear scale (apologies for terminology) it's just runs at a constant speed.
I'll let the engineer have input from your input though.

 

[JohnD]

I mean, change the speed manually, not switch it on. My Grundfos Alpha (yours may be different) governs its speed down automatically according to load, so runs slower in summer; but it also has manual settings.

Pumps usually have a small grey or black plastic knob that you can rotate to adjust speed. Likely to be on the plastic box where the cable goes in. If you change it, make a note of where it was before, so you can turn it back afterwards. Most pumps just have speeds 1, 2 and 3.

On this example, it is red http://www.screwfix.com/p/wilo-4035479-sb30-secondary-circulating-pump/74599#

and this one is grey http://www.screwfix.com/p/flomasta-central-heating-pump/87773

If you have a sediment blockage, I don't suppose this will help. You might consider having a system filter fitted to capture future circulating particles.

 

[Beardie]

Ah ok...I don't have the fixed speed pump as you referenced.
Mine is a wilo http://www.screwfix.com/p/flomasta-central-heating-circulating-pump-230v/45357
With variable load speed, but thanks for the info anyway.

I have a sentinel eliminator fitted but this was after I started getting the short cycling, so as holty and agile have suggested, it's probably a clogged Hex that needs clearing with a proper flush , cleanse and refill with inhibitors...

Any recommended installers most welcome to drop me a line...happy to pay proper rates for a proper job....

 

[Agile]

Just a note nobody on Worcester list has to sell boilers.... I'm on "Worcester list" and i fit what I think is best for the job and customer.

You seem to be a rare exception.

Most I come across and most we see referred to here just blindly quote for Worcesters all the time.

The reality is that some boilers are better for some customers and situations.

One replacement I am looking at next week would probably suit a Worcs 12Ri because its in the living room and that boiler is very quiet and looks nice!

Tony

 

[Dan Robinson]

Funny that Norfolk. .... I was on the Worcester list, but was booted off due to not fitting enough.

Sorry Worcester. I fit the right product for the job. Not to please YOUR sales figures.

 

[Beardie]

Interesting responses, re Worcester. Will have to deliberate on whether I bring this up with the engineer....I do know he said he has not had much success with flushing vitodens...but will see if he is confident enough to be successful. If he is not I will seek other quotes from engineers on the viessman list...