confused on which boiler to choose

[bengasman]

I would expect 15% saving minimum on a like for like basis with weather compensation.

You clearly have never designed and installed a ch system on a HE boiler, nor read the spec from the manufacturer.

 

[CharteredEngineer]

Viessmann quote 15%, if you can understand German and read test.de, they also quote more than 15% for WC.

 

[simond]

As a chartered engineer (I am laughing here) clearly you haven't read the CIBSE reports on the merits or otherwise of oversizing radiators?

 

[CharteredEngineer]

I would expect 15% saving minimum on a like for like basis with weather compensation.

You clearly have never designed and installed a ch system on a HE boiler, nor read the spec from the manufacturer.

Nope, I just work in the technical department for a well known manufacturer of various types of heating equipment.

 

[CharteredEngineer]

As a chartered engineer (I am laughing here) clearly you haven't read the CIBSE reports on the merits or otherwise of oversizing radiators?

In my humble opinion, the UK is lagging well behind the Dutch, the Germans and the Scandinavians on heating systems. CIBSE research is generally in partnership with vocational colleges around the country. Don't take this the wrong way but there is a bit of a difference between their research and for example BDR in Appeldoorn or Viessmann in Allendorf.

Just as a cost comparison, Remeha avanta WC kit is £45inc.vat, you'll get that back within 2 years even if you have 5% efficiency gain.

 

[mickyg]

I would expect 15% saving minimum on a like for like basis with weather compensation.

what you expect and what happens don't always coincide

 

[simond]

I'm not disputing that WC makes a saving.

My main issue with it (apart from a vocal minority here promoting it as the Second Coming) is that the controls from Viessmann and Vaillant (for example) are unfathomable to the average householder.

We started fitting these two products with WC in 2005 and had a stream of complaints re: ergonomics of the controls. In fact, at customer request, we took at least three out and replaced with Honeywell programmable stats.

The Remeha WC system can be invoked in a simpler way, but their boilers are unreliable junk from my personal experience. Their condense traps would be downmarket in M Mouse's house.

 

[adlplumbing]

charted your forgeting one very important thing the avarage person buying a boiler in this country only cares about one thing the bottom dollar
all these thingss add up and they don`t like it

 

[transam]

O.P go with the baxi i would say , Veissman? there have been a few posts on them weaseling out of there warrantys of late , think they may also be in the put a deposit down before they turn out game (scam maybe ?) alledgedly, maybe ? possibly ?

 

[bengasman]

Viessmann quote 15%, if you can understand German and read test.de, they also quote more than 15% for WC.

15-20% of the difference between band d and a; not 15% of the total. If you're so good at German, how come you didn't pick that up?

In reality, the saving is not even that. Provided the installation was designed and installed properly, the return temp is about 20 degrees lower than the flow. Therefore, wc only makes a noticeable difference when the flow temperature is above 75, and virtually nothing below 70. That in turn means, that the wc will not do anything for about 55 minutes out of the hour that the heating is on, unless the boilerstat is screwed up to max. If the boiler stat is set below 75, the wc will do virtually nothing to save money at any time because the cycle will only bring the return temperature near the 55 for a few moments before the boiler clicks off.
If you are such a clever engineer, how come you did not pick that bit up?

 

[mysteryman]

You are, as ever, missing the point. The FLOW temperature needs to be below 53C for full condensation to occur, and properly set up weather comp will achieve this for about 95% of the heating season, even with conventionally sized radiators. Cycling as such is largely eliminated, as the boiler modulates continuously - unless it is grossly oversized.

Installers [and armchair experts] come into two categories - those who understand, and set up their systems correctly in consultation with their customers, and those who just will not accept progress.

 

[simond]

I am not a category, I am a free man

 

[BGEngineer]

Yeah but this was the whole point, luke warm rads are no good to anyone when its -5C outside.

 

[mysteryman]

What is it with you guys?

This does not happen with properly set up weather comp.

 

[bengasman]

You are, as ever, missing the point. The FLOW temperature needs to be below 53C for full condensation to occur,

So what would you say should the return temp be?