Boiler quote - questions to ask..

I’d always had Viesmann, but went with a Baxi this time as it had got the longest warranty/cost differential. It’s a white box that heats the water to me, I’m sure most of the difference is which boiler the installer prefers to fit or service and gets familiar with. Like bikes, I don’t think there’s many real turds around these days.

Price it up on one of the many boiler quote sites.

Check warranty as with worc Bosch it seems to vary based on supplier status but we got 10 yrs on ours. (*seem to get 12 with some suppliers)

Yes - I've got Heatable/Boxt quotes to compare with - they've gone up by £700 since beginning of Nov so I thought I'd get a local quote.

Check the % efficiency. Ideal make ones which are better than Viesmann. An extra 1/2% adds up over time.

That's some increase since November.

Depends on age of current one. Ours is very old and needs a lot of new pipe work to bring up to standard and recent regs. Boxt only picked this up the day before installation and upped their quote by about £900. Got a number of other quotes and theirs seemed ok price wise in the end but I was concerned that they may spot more things and hike it on the day, so I am going with homeserve who are a bit pricier but seem to have identified a number of items (which I have confirmed are valid) and provided a fixed quote and a 10 yr guarantee.

That’s some increase since November.

Yup - Viessmann was £3600 on 7th Nov. It's £4300 now. I did include moving to a new location in the quote so if I left it where it was it would be cheaper but still, it's a big jump.

Length of warranty is up there on the list of queries, plus what you need to do to maintain that warranty.

WB require a service every year to maintain. When we had a Viessmann it was only after 5 years it needed an annual service. To me that speaks volumes about how good they think their product is.

Our Viessmann boiler was very good and had an external temperature sensor on the outside of the house which meant it only worked hard when it needed to. Our current WB outputs the same regardless of outside temp.

Have you got a Smart thermostat ? ie EvoHome or Drayton Wiser etc? It will be an extra additional cost, but will save you further installation costs in the future. Get the base unit of choice and then add smart TRV's as and when you can afford it.

I've got a Hive thermostat (combi boiler). I only have a couple of TRVs (not smart Hive ones though) on two newer rads installed about 10 years ago.

Viessemann or Vaillant.

Viessemann also do a high temp (Up to 70Celsius) ASHP. https://www.viessmann.co.uk/en/products/heat-pump/vitocal-range.html

What’s the likely cost of an ASHP? I filled in the details on the Viessmann quote request but it says due to increased demand they aren’t doing any quotes till the new year.

I do like the idea of an ASHP if they work OK and don’t cost £10k to install…

Based on very recent experience... will they be fitting a shock arrester as part of the install, and please can you check water pressure is within tolerances of the boiler. Thankfully repairs covered under Worcester Bosch warranty, but a faff/wet mess all the same.

When we had a Viessmann it was only after 5 years it needed an annual service. To me that speaks volumes about how good they think their product is.

That sounds incorrect. I've never heard of any boiler manufacturer say that and it's not legal for rental accommodation and not advisable for your own property.
As it's Viessmann probably a poor translation of the manual. Not that they are unclear generally from them usually...

Baxi or Worcester then Ideal depending on how much you want to pay for warranty and what you can actually physically buy.

I would ask about getting a weather compensating controller installed with the boiler. That way it can modulate the flow temperature to maximise condensing efficiency and prolong the life of the boiler instead of running the boiler flat out all the time.

Dunno about new boilers, but based on this years research I'd like (not neseceraly as part of the boiler, but would need doing at the same time)

Automatic bypas valve so the last of the rads could be on TRV's.
Better modulation of it's duty.
Ability to modulate pump speed because it's more efficient when the system is cold to run the pump fast, and more efficient when it's warm to run it slow.

That said, it's probably marginal gains, and it's a tossup whether those changes save more than spending it on more insulation. We had the wall cavities done this year and the controller packed up on our heating last night. There was a frost this morning but the house was still acceptably* warm 🤷‍♂️ , last year it was always freezing at 6am until the heating came on.

*i.e. it's far from warm, but i wasn't jumping straight out of bed into a jumper.

We had a new Vaillant fitted and it failed within 2 months - Vaillant fixed it under guarantee (heat exchanger and a circuit board were borked) but it took nearly a week to get them out and that was in September before the peak of boiler breakdowns.

A family member had a Worcester Bosch fitted by a platinum installer and had no end of problems with it. WB warranty service was absolutely atrocious - endless calls to get them to acknowledge the fault, delays of up to 2 weeks to even come out, then they haven't got the parts, then they fit 2nd hand parts, then it fails again etc etc. They may well come with a 10 year guarantee but aren't set up to make good on that.

Ask them to talk you through the heat loss calculations they’ve done for your house in order to determine the size of boiler required. Most plumbers just seem to suck their teeth and go “oh, it’s got x beds and y rads, so it’ll be whateverKW”. This means you can end up with something way too big that pisses gas away.

You also want to know how they’re going to configure it for the most efficient running. Rather than just install and run.

So, he's recommended a Baxi as it has good warranty (10yrs)/availability of spares, brass components and a stainless heat exchanger. About £600-£800 less than the WB options from Heatable.

Sounds good to me. We've gone WB via boxt 3 yrs ago - fitted next day. We've needed to use the warranty but couldn't fault the service, other than that the boxt engineer wasn't able to tackle the warranty repair so had to triage and refer onto WB. Both were out within 24 hours, but that added up to 48 hours of swapping buckets beneath a 3 y/o boiler. Simply raising this as others have had issues and ours has been a reasonably positive experience.

The issue we had (apparently not uncommon) with our previous WB is that the plastic parts fail, typically in yrs 9-13 (according to heavily gold-benecklaced, baxi jacket wearing and tanned indy gas engineer just back from Dubai and with a new mercedes) and you get into a repetitive cycle of £200 repairs - none in isolation equate to new boiler... I am anticipating the same with this one in a few years, prob should have gone Baxi... but v young kids, urgent need, busy job meant we just went with what we knew.

He did have a Baxi jacket and baseball cap on 😂 but what you said about plastic parts in the WB he also said, so good to have independent corroboration that he wasn’t talking bollox!

Prob get him to do it based on that.

No sure getting an exact size of boiler is essential for economy. Modern boilers modulate. For example our WB Greenstar 4000 can throttle down to 10% of output when full output isn't required.

https://www.worcester-bosch.co.uk/about/news/our-brand-new-greenstar-4000-boiler

Of course it needs to be big enough. And if running a combi boiler a bigger boiler gives a faster hot water flow.

Well current boiler is 30kW and we’ve had an extension with a shower so a bigger one is probably sensible and the only options are 36kw and 40kW so it’s not an exact science. Like you say they modulate and he suggested 36kW or 40 if I wanted the bath filled quicker - so 36 is going to be the one.