SEDBUK A open vent boilers

[zebu]

Which are the most reliable open vent boilers with SEDBUK rating A?
I've been advised against getting a combination boiler, as there is space (and an F&E tank) for an open vent boiler. However I've heard that some open vent boilers in practice make assumptions that hold in a pressurised system but that are not likely to hold in a fairly old radiator open vent setup such as mine. Perhaps these boilers are really just reworked versions of combination boilers. Some of those that aren't have SEDBUK rating B only, which is presumably on its way out.

 

[Rico99]

Zebu,

Look on here it lists the rating fro all boilers.

http://www.sedbuk.com/

Rico

 

[zebu]

Thanks, Rico. I've heard that some of the open vent boilers with SEDBUK rating A don't behave well: they are best suited to pressurised systems. I'd like to know which ones behave well.

 

[GPlumb]

Why do you want a open system? converting to a sealed system is easy and gets rid of the wet loft.

Bigger choice of boilers as you can see.

 

[zebu]

I've been recommended an open vent system because of its flexibility(with an immersion heater for HW, for example), higher flow rates and absence of pressurising. When starting from scratch the answer would be different, but I already have the plumbing and space for the replacement boiler and cylinder, and the pipework to the radiators is elderly (so with a pressurised system the pressure might need frequent tweaks).

 

[EliteHeat]

I've been recommended an open vent system because of its flexibility(with an immersion heater for HW, for example), higher flow rates and absence of pressurising. When starting from scratch the answer would be different, but I already have the plumbing and space for the replacement boiler and cylinder, and the pipework to the radiators is elderly (so with a pressurised system the pressure might need frequent tweaks).

Unless you have pipe-work of unknown provinence buried in screed, you should have no worries re a system boiler. If you really want an open vented 'A' rated one, worcester do a good 'un.

 

[zebu]

Thanks, EliteHeat. Does the Worcester have an aluminium alloy heat exhanger? Is this likely to cause problems?

 

[simond]

The Worcester Ri is bit of a cheapy product with a cost reduced heat exchanger.

The better Worcester models, designated CDi, start at 30Kw and use a German Junkers Heatcell 5 heat exchanger.

Other models we fit for this application are the Vaillant 4 series, Viessmann Compact 100W, and Broag 18v and 24v. We have just had an instance of shoddy workmanship on a Broag 35C today, (missing rivet on the casing), which has cost us a lot of time.

But then you will read all sorts of contrasting advice here and elsewhere. In some ways, the more (ahem!) research you do, the more confusing the result on the internet.

In my opinion, the best boiler for open vent is the Buderus 19R, but the UK arm of Bosch (Worcester) have recently pulled all the Buderus boilers out of the UK. Didn't like the competition I imagine.

 

[EliteHeat]

Thanks, EliteHeat. Does the Worcester have an aluminium alloy heat exhanger? Is this likely to cause problems?

All WB's do I believe and I dunno, I just install them. No doubt some clever monkey will proceed to give you a metalurgical analysis etc 'cos there are a lot like that here!

The Worcester Ri is bit of a cheapy product with a cost reduced heat exchanger.

The better Worcester models, designated CDi, start at 30Kw and use a German Junkers Heatcell 5 heat exchanger.

Ha! no sooner said

 

[simond]

I can't do the analysis you mention, but at least I can spell it.

Metallurgical.

 

[bengasman]

there really is not a single argument if favor of installing an open vent boiler.
you might as well take the opportunity and enter the 21st century, although keeping an unvented cylinder and the tank is rather arguable.

 

[sloppytom]

you cant beat the baxi promax. easiest to install. not expensive, reliable, and still uses a bigger heat exchanger so no need to run any more cables for a pump overrun, yet you still get the sedbuk A efficiency

 

[swbjackson]

It's a Potterton Promax or a Baxi Solo. More or less identical although the Promax appears to be a slightly cut down version.

They seem to be a good bet on older systems where you can't guarantee how the existing pipe work runs. I just wish they made the tails a wee bit longer so it's easier to get a compression fitting on.

Mike

 

[BigBurner]

It's a Potterton Promax or a Baxi Solo. More or less identical although the Promax appears to be a slightly cut down version.

The Promax is the old Baxi Barcelona, which was junk. Avoid any Britsh boiler, Ideal, Baxi. Pott, Ravenheat.

 

[BigBurner]

there really is not a single argument if favor of installing an open vent boiler.
you might as well take the opportunity and enter the 21st century, although keeping an unvented cylinder and the tank is rather arguable.

He needs to test his cold water mains for pressure and flow. If good enough fit a Broag 35C or 39C combi. http://www.avantaplus.co.uk Better than Vailliant with integral weather compensation throw in, and great value for money with a 5 years guarantee. Buy the outside temperature sensor and set it up (easy to do). And then get right into the 21st century with high pressure showers. Keeping old tanks and cylinders around is problems for the near future and more money - and leaks.

Whoever advised him clearly hasn't much of a clue.