New boiler choice ?

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As some may know from a recent post on yet another breakdown with my ageing Baxi Barcelona, it needs to be replaced.

Requirement 30kW Cas Condensing boiler, wall-mounted, horizontal flue. Heat only

It is connected to a pressurised thermal store, so only contents of the store circulated around the boiler. The control system of DHW/heating requires that it can run pump only when it needs to. (details attached in a simplified view, and as full system ..if interested, or unfamiliar with a store)

It's a very good system in use.

My initial thought was a Vaillant, but they advise that their HEAT only is open vent and cannot connect to a Pressurised store, only their system boilers - but that then stops system control operating the pump only

The next option was an Intergas - but the only registered installer for my area (advised by Intergas) has said I'm outside of his normal area .. (1.5 Hrs away), he seemed not very keen on the job.

BAXI advised using their BAXI 830 HEAT ...

What other suggestions, not sure if Viessman, Worcester are well rated.
 

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1. I have a heat only Vaillant, connected to a sealed system with separate expansion vessel. No issues and its in accordance with the Vaillant installation instructions.
2. A lot of Vaillants now have aluminium heat exchangers, rather than stainless steel, and I've rather gone off them as a result.
3. Out of interest, what pressure do you run the pressurised store at, and how is it pressurised?
 
#1 I spoke to Vaillant this week - they advised their REGULAR boilers cannot be connected to a pressurised thermal store. In fact they even refer to them as Open Vent boilers They advised the only boiler they make that can connect to Pressurised Thermal store is their System boiler.

#2 The REGULAR boilers have aluminium HEX only their SYSTEM boilers has SS Hex

#3 Thermal store is pressurised at 1bar, there is a standard filling loop attached to the Expansion chamber - pressurise with that. It's one of these : https://www.bes.co.uk/expansion-vessel-18-litres-20245/
 

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I'd still recommend Intergas. You don't need to be one of their registered installers to get the full warranty, and they're very suitable for thermal stores as they can be set to higher temperatures than most other boilers out there. That being said, a thermal store is a terribly inefficient way of running a condensing boiler. They run too hot so the boiler will rarely actually condense. Worth considering changing over to an unvented cylinder, which will give you the same or better hot water performance and allow you to get the best out of the boiler in terms of efficiency.
 
Look at Ideal Logic +
10 year warranty, have fitted a few and service many, very little issues. What issues there are, plenty room to sort out too.
All boilers must be serviced according to makers guide lines and not MOT tested with an analyser and call THAT a service.

Read your other post. What happened to you is quite common. Fault finding is an art that is developed over time. Guess work does not make a good engineer
 

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