Which combi boiler replacement? Vaillant EcoFit Pure vs Baxi 800 vs Ideal Logic 2

juliushibert

My 14-year-old Vaillant Ecomax 30 combi has died and repair quote is £1,000, so replacing seems the sensible option.

Property: 2 bed + box room terrace, East of England. Single heating zone, manual TRVs on radiators. This is our long-term home.

Current setup: Tado X thermostat (wireless) which I’d like to keep/reuse if possible.

Got three quotes back, all around 30kW:

1. Vaillant EcoFit Pure 30kW - £2,820 inc VAT (10yr parts & labour warranty)

2. Baxi 800 30kW - £2,952 inc VAT (10yr manufacturer warranty)

3. Ideal Logic 2 30kW - £2,498 inc VAT (10yr warranty)

Questions:

• Any strong preferences between these three? All seem reputable but I’m torn

• The Ideal is noticeably cheaper - is there a catch, or is it just good value?

• Anything else I should be asking the installers or considering?

All three plumbers seem decent with good reviews. Just want to make sure I’m not missing something obvious before committing £2.5-3k!

Thanks in advance for any wisdom!

WIAWSNB

What protocol does the Tado X use? Eg, Opentherm or what? Check which boilers are compatible.
Personally I'd also check each for having a Stainless Steel main heat exchanger - the 'engine'.
Tbh, I doubt an aluminium one would let you down these days, but traditionally they weren't as good - susceptible to corrosion.
These are combi boilers? Their performances will be pretty much identical.
Anything else that could tweak out a slight efficiency advantage, I wonder? Perhaps 'weather compensation' - find out (ask each manufacturer, for example) what they have. The idea is that the boiler will reduce its output temp in milder weather, making the boiler more efficient. 
In terms of reliability, I've no idea.

juliushibert

Thank you. 

The tado x says it works with Relay or OpenTherm. 

From the list of boilers I posted I believe the Baxi and Ideal both use really or OpenTherm. 

I have been led to believe the Vaillant ones tend to only use relay or their own eBus protocol. 

One plumber said they thought OpenTherm was a waste of time and ‘they wouldn’t fit it in their own house’ and they install boilers all the time. Is it not worth it?

retiredbanker1

Just had a Worcester 400 25kw Boiler fitted to replace a 32 year old boiler for £3000.

WIAWSNB

juliushibert said:

Thank you. 

The tado x says it works with Relay or OpenTherm. 

From the list of boilers I posted I believe the Baxi and Ideal both use really or OpenTherm. 

I have been led to believe the Vaillant ones tend to only use relay or their own eBus protocol. 

One plumber said they thought OpenTherm was a waste of time and ‘they wouldn’t fit it in their own house’ and they install boilers all the time. Is it not worth it?

Cool - you've done your research!
Ok, how does a normal room stat like my Hive work? I set it to, say, 18oC, and when the room reaches that temp, it turns off the boiler. When the temp drops a bit, it turns the boiler back on. When it reaches again, it's offski again. I think it's a touch more sophisticated than that, but that's pretty much it - the boiler tries to output the same water temp at all times, as this temp has been set at the boiler.
How does Opentherm work? You set your room temp to the same 18oC, and the stat tells the boiler how far away from achieving that temp it is. If a few degrees away, it'll turn the boiler output up a commensurate amount to get you there. However, as the actual room temp approaches the set temp - say it's at 17oC - then the stat will tell the boiler to start modulating down and lower it's outputted water temp. By the time you get to 18oC, the boiler is likely at its lowest output - 'ticking over' - so it'll maintain that temp with a reduced water temp - the rads will run cooler, but keep on running.
What difference does this make? 1) it'll keep the room temp more stable. 2) it'll reduce the number of off-and-ons of the boiler, reducing wear, 3) a cooled water output temp = a cooler return temp = a more efficient boiler = energy savings.
Ok, I don't know how much better this makes it, but it is clearly 'better' in terms of efficiency, comfort, and reduced wear. So I suspect that GasSafe was old-school.