Current opinion about Vaillant EcoTec Plus 428?

[ScottishGasMan]

I reckon it's because on standard efficiency range rateable boilers you couldn't really go wrong, high water content could take over heating and general abuse, and setting a low burner pressure sorted most issues, and allowed for future expansion,

Premix zero governor boilers can only turn down so much, generally not nearly as much as std efficiency units, also they must light at a semi high rate, normally around 3/4 full power, so oversizing besides lowering efficiency also causes noise and cycling issues that often can't be overcome

 

[ScottishGasMan]

I always wonder what installers are thinking of when they replace an 18 kW boiler with a 28 kW boiler!

Do they just not understand boiler sizing?

Or has the existing 18 kW boiler been unable to properly heat the house?

Tony

Combis are 28kw so they must need the same on a heat only

 

[simond]

Advantage on 4xx is that generic diverter valves (apart from the one on the unvented as needs to be as per MI)can be used and external pump think the turndown ratio may have been improved recently as well but would get that confirmed. 6xx no external pump or diverter valves (apart from the required one for the unvented)

This simply isn't true, the 6 series has to be used with generic diverter valves (none are inside the boiler).

The 4 series is a rebadged Glowworm cheapy sold at a premium.

6 series ecoTec+ is part of a 10yr warranty offer till the end of July, conditions apply.

 

[D_Hailsham]

We are about to embark on a refurb of a 1930's brick and tile detached 4 bed house. ...He has specified a Vaillant EcoTec Plus 428 boiler

Are you extending the house? If so, this could account for the larger boiler. Even so, 28kW does sound excessive.

It would be helpful if you could post the installer's reasons.

 

[Marmottefarcie]

We are about to embark on a refurb of a 1930's brick and tile detached 4 bed house. ...He has specified a Vaillant EcoTec Plus 428 boiler

Are you extending the house? If so, this could account for the larger boiler. Even so, 28kW does sound excessive.

It would be helpful if you could post the installer's reasons.

The installer has yet to come up with any reasons behind his spec. It's becoming more & more apparent that he doesn't really have much of an idea. We are more than slightly concerned about his ability to marry the new set up to the underfloor heating successfully.

 

[scoobydo123]

Yes of course 6xx diverter valve statement was duff sorry bout that! Still maintain not sure why 4xx when it sounded like it was being converted to sealed. When did the turndown ratio get revised for 4 xx.

cheers

 

[Steelmasons]

A little information/knowledge can be dangerous Scooby.

 

[ServiceNumpty]

Installers probably looked at the 28kw, because they've also included the coil rating for the unvented cylinder.

 

[Agile]

Installers probably looked at the 28kw, because they've also included the coil rating for the unvented cylinder.

Quite possibly, but the addition to add is only 2 kW rather than the full possible maximum absorption.

Tony

 

[DP]

Installers probably looked at the 28kw, because they've also included the coil rating for the unvented cylinder.

Tend to agree there. With coil rated at some 24kW,. boiler needs guts to heat water in specified time. Smaller output will do the job as well, but take longer

 

[Marmottefarcie]

We are about to embark on a refurb of a 1930's brick and tile detached 4 bed house. ...He has specified a Vaillant EcoTec Plus 428 boiler

Are you extending the house? If so, this could account for the larger boiler. Even so, 28kW does sound excessive.

It would be helpful if you could post the installer's reasons.

Update: I just received the installers reasoning (now that he's back from holiday):
"The gas boiler we have chosen for this quote is a Vaillant Ecotec plus 428, the reason for this is because of any extra radiators or underfloor heating to be added to the house, also this boiler can be downrated, this means it can be set up of the K watt output for the house once all work has be completed, if we use a 418 we will have no extra k Watt output if we require more, the other reason we use this boiler and not the sealed system type boiler is that the vessel built into the boiler is to small and this will make the system over pressure rise."
I also queried his spec of a Honeywell 927 room thermostat rather than Vaillant specific control systems to control the underfloor heating.
His response:
"The under floor system, we would use poly plumb for this and will have a separate zone for this, this will be controlled by a Honeywell 927 room thermostat"

I am going to get a quote from an underfloor heating specialist heating engineer because the response from the builders plumber doesn't convince me that he has even calculated the requirements of the house before spec ing the proposed new system.
Any comments?

 

[ScottishGasMan]

While the boilers maximum heat output can be down rated, it's neither efficient or correct to fling in a massively oversized one.

The sealed unit comes with a small vessel yes, but as with any sealed boiler it's simply a case of buying an external vessel and fitting next to or near the boiler (there not expensive)

Especially the 4 series boiler I'd have a massive concern about oversizing it, you house heat loss is what it is, unless your building an extension which is unlikely to need 10kw being built to modern regs.

 

[ScottishGasMan]

Oh ps, I can see the point of using Honeywell 240v controls when there is multiple zones/ufh

If your using the vaillant cylinder then it's worth the complication of the vaillant controls for the ability to use the cylinder ntc rather than a stat. But from a users point of view, you'd probably never know the difference

 

[Dan Robinson]

SGM - isa now a good time to tell you there is a Bunny accessory to allow Evo to talk Opentherm to the boiler?

 

[ScottishGasMan]