Viessmann Vitodens 200-W

[Paz328]

Now we have a DIYer apparently designing his system on the basis of what Sanj is writing. It is the blind leading the blind. Sometimes the internet is a misleading place full of fools.

If you're referring to me as the DIYer, I'm not designing my system based on what Sanj is saying. To clarify, I took the opportunity to change my radiators while redecorating as the rads were leaking and rusty. I used the radcalcs.com website (recommended on this site) to help determine the size of radiator required. I was now wondering whether the rads sizes were correct to gain the benefits of weather comp. I'd be very interested in you're answer to my question re rad sizes as you have installed many Viessmann systems.

The internet is indeed is very misleading place, not helped by the fact that "experts" can't agree on the same issues!

 

[simond]

Balenza wrote;

Amatuers.

Oh, the irony.

Consider learning how to spell 'amateur' if it is an insult you intend to use regularly.

 

[sanj.varah]

This Sanj chap is not a heating installer. Furthermore he seems adept at confusing the truth.
We have had tales of DIN threads being needed when this is total fiction.

You're damn right i'm not a heating "installer". I regard the average "installer" (and stick yourself into that bracket) as a plank who has little more than a few GCSE's and a City And Guilds. Who fundamentally has about as much knowledge as a 7 year old.

If it will shut you up, i'll take a picture of my jig and demonstrate that the Vitodens 300 is designed for threaded pipe.

He has been recommending boilers that are no longer imported into the UK.

I suggested the poster get a Vitodens 300W. Now you say that they aren't going to import it because you have a direct line to the MD at Viessmann UK.

He has been making claims of 40% for adding weather compensation when now he is backtracking and saying that his 40% efficiency was the total net benefit of rowing out a Halstead Balmoral, FFS! Which is what we could have told him at the start.

I think you meant throwing? I still think the Viessmann controls add a substantial amount of efficiency over a bog standard condensing boiler. But how would you know your understanding of control loops is limited to what you learned on the Installer course. Actually figure out how a PID controller works and then come back.

As usual, some misguided fool agreed with his 40% claim, even though Viessmann were on file as only expecting a max of 15% efficiency gain with weather comp.

I don't think balenza is misguided at all.

 

[tonybhoy]

Now we have a DIYer apparently designing his system on the basis of what Sanj is writing. It is the blind leading the blind. Sometimes the internet is a misleading place full of fools.

If you're referring to me as the DIYer, I'm not designing my system based on what Sanj is saying. To clarify, I took the opportunity to change my radiators while redecorating as the rads were leaking and rusty. I used the radcalcs.com website (recommended on this site) to help determine the size of radiator required. I was now wondering whether the rads sizes were correct to gain the benefits of weather comp. I'd be very interested in you're answer to my question re rad sizes as you have installed many Viessmann systems.

The internet is indeed is very misleading place, not helped by the fact that "experts" can't agree on the same issues!

You have to oversize the rads in order to gain from condensing boiler efficiencies.

Condensing boilers are not being recommended and installed for efficiency but for low nox .I.E. they are less polluting however if you have one and have a large house with massive rads and no trvs then you are going to save a fortune on your gas bill relative to an old Ideal concord, for example.


The more you spend on gas the more you will save on your fuel bills.

The more water you have in your system means you are more likely to save loads of money if you go down the condensing route with decent controls however if your house is extremely well insulated is not too big and has TRVs fitted then you ain't gonna save that much except the environment.

And,BTW anyone who thinks that Viessman made the claim they did because of possible legal issues is at best delusional.

Viessman made that claim because that is how much of a saving that you can reasonably expect to make.

Viessman were talking to other manufacturers such as WB in that letter they weren't really speaking to gas installers and they were very careful not appear to be make outlandish claims vis fuel saving.

They were in effect throwing down a gauntlet to the likes of WB who after all are Viessman's main competitor and who are not interested in WC at this point.

 

[simond]

You're damn right i'm not a heating "installer". I regard the average "installer" (and stick yourself into that bracket) as a plank who has little more than a few GCSE's and a City And Guilds. Who fundamentally has about as much knowledge as a 7 year old.

Is that why you are on the forum, to educate us?

Let us just remind ourselves how many boilers you have fitted in your life, it's somewhere between 0 and 1, isn't it?

You are offering to take a picture of your boiler to prove to us that we have never connected a pipe to one. We just fit karzis, I suppose?

Furthermore, having been informed that the manufacturer suggests that invoking the optional WC to their boiler could glean a 15% efficiency benefit - you still maintain that your earlier stated 40% saving can be achieved and the lower Viessmann figure is to prevent legal action.

Those of us with our GSCEs and underdeveloped brains know that it is pretty rare for a manufacturer to understate their efficiency.

It is amazing that a man can learn so much from only fitting ONE unit. And how altruistic of you to share that knowledge with us here. You are either a genius.

Or a fantasist.

 

[billy bob]

tonybhoy, I don't know if the term oversizing the radiators for condensing boilers is the correct way to put it, the radiators should to be sized to run at a lower temperature to gain the most efficiency from the boiler, the radiators will be larger than if they had been sized to run at the usual higher temperature of a heating system, I am not criticising you, I agree with what you have said in your post, but I think if we used the terminology Size the radiators to run at a lower temperature for condensing boilers, it would stop some of the usuals from whinging and criticising, although they are incorrect.

 

[drboilerfix]

As for spares I think Viessmann are in the UK for the long haul as they are a privately owned family business not like a lot of the other private equity cowboys. I think the spare situation is something to do with politics regarding those robbing b******s parts center.
I have fitted 2 200 W 35kw combis and the hot water performance is ok..

 

[tonybhoy]

tonybhoy, I don't know if the term oversizing the radiators for condensing boilers is the correct way to put it, the radiators should to be sized to run at a lower temperature to gain the most efficiency from the boiler, the radiators will be larger than if they had been sized to run at the usual higher temperature of a heating system, I am not criticising you, I agree with what you have said in your post, but I think if we used the terminology Size the radiators to run at a lower temperature for condensing boilers, it would stop some of the usuals from whinging and criticising, although they are incorrect.

Yeah,you are of course correct BB.

My bad.I'm just an old fashioned tradesman who is basically coming from the angle that most older properties rads are way too big anyway and are pretty useful in terms of condensing boilers and efficiency.

Obviously if your going to install from scratch then the rads should be sized accordingly,as you point out.

Cheers,

 

[billy bob]

tonybhoy, I don't know if the term oversizing the radiators for condensing boilers is the correct way to put it, the radiators should to be sized to run at a lower temperature to gain the most efficiency from the boiler, the radiators will be larger than if they had been sized to run at the usual higher temperature of a heating system, I am not criticising you, I agree with what you have said in your post, but I think if we used the terminology Size the radiators to run at a lower temperature for condensing boilers, it would stop some of the usuals from whinging and criticising, although they are incorrect.

Yeah,you are of course correct BB.

My bad.I'm just an old fashioned tradesman who is basically coming from the angle that most older properties rads are way too big anyway and are pretty useful in terms of condensing boilers and efficiency.

Obviously if your going to install from scratch then the rads should be sized accordingly,as you point out.

Cheers,

Absolutely, most radiators were oversized and should cope with lower temperatures and still give the correct temperature for the room, as long as the correct controls are added

 

[Agile]

I would always be worried about ordering from a supplier who hides their postal address!

If they failed to deliver and kept the payment then there is no address to serve the Court claim at !

Furthermore, as far as anyone can guess, this may just be a scam to collect payment and deliver nothing!

 

[kevplumb]

getting better this one is only 2 years old

 

[Agile]

... and if they were, Viessmann would be on to them at once!

It is crazy to fit a condensing boiler without weather compensation - that is what keeps the boiler condensing.

And Viessmann would get no closer than their web site without a physical address!

If they were genuine and supported by Viessmann then they would be listed on the Viessmann web site. But why would Viessmann want to bypass their own ( slow ) parts supply operation?

Its also crazy of Viessmann to sell the new 200 WITHOUT the Vitrotronic W/C unit already fitted. No one would choose that model over the 100 unless they were planning to fit W/C. There must be a lot of constant temperature controls sitting unused!

Alternatively the boiler should be supplied WITHOUT any control unit to keep the cost down. That supplied unit must add at least £40 to the boiler cost. Without it it would be £40 more competitive.

Tony

 

[D_Hailsham]

I would always be worried about ordering from a supplier who hides their postal address!

If they failed to deliver and kept the payment then there is no address to serve the Court claim at !

You have to hunt, but the info is there!

"The term ‘Clipper Enterprises Limited (trading as Viessmann Spares Direct)’ or ‘us’ or ‘we’ refers to the owner of the website whose registered office is Unit 8, The Centurion Centre, Castlegate Business Park, Old Sarum, Salisbury, Wiltshire, SP4 6QX, United Kingdom. Our company registration number is 7047839, registered in England and Wales"

You do not have to oversize radiators - the boiler and weather comp will keep the system below dew point and therefore condensing almost all of the heating season.

Surely it depends on the design flow and return temperatures? Let's say you size the radiators assuming the BSI EN 442 temperatures of 75/65/20 and an outside temperature of -1C. Then, assuming condensing does not occur until the return temperature drops below 55C and the differential is still 10C (i.e 65/55/20), the rads will now give off 75% of their stated output, which is equivalent to an outside temperature of 5C. So while the temperature is below 5C the boiler will not be condensing. If, on the other hand, you oversize the rads by a third, the boiler will be condensing when it is -1C outside.

Many houses which have been properly insulated since the rads were put in, already have oversized rads; for example, I have 13kw of rads but now need only 6.5kW. This means I could run the heating at 65/55/21 at an external temperature of -8C.

Just waiting for the existing boiler to pack up ...

 

[mysteryman]

*******

 

[D_Hailsham]

I have a Viessmann Vitodens 300 combi with weather compensation. The flow temperature never rose above 59C in the last two very cold winters, and we were comfortably warm. Thus the boiler was almost fully condensing even in the severest weather. Therefore I am confident that you do not HAVE to oversize rads for condensing boilers.

Have you ever done a heat loss calculation for your house and compared that with the total output of your rads? You will probably find that the rads are oversized!

The [primary] flow temperature never exceeds 49C in DHW heating, so it is fully condensing.

At what temperature does the hot water leave the tap?