Questions regarding Boiler replacement

andre_xs

Dear All,
Thanks for all the input in the previous threads about the replacement of our boiler. We now had 4 engineers here. One we wouldn't employ just based on the visit, leaving 3 companies. We now need to choose one :-)

All companies have very good ratings on usual platforms (TrustATrader, Google, MyBuilder,...). Companies 1 and 3 are larger in the local area (600 - 1600 reviews on TrustATrader), company 2 seems to be a smaller family company ("... and sons", 160 reviews, no reviews on Google)

Quotes vary in price. These are pretty much like-for-like quotes, including Power or Chemical flush and moving boiler from kitchen to adjacent conservatory (incl change of pipe works). This is in a town just outside the M25/London area.

1) Company 1: Vaillant Ecofit pure 825. £3850 - max £4100. Powerflush included
2) Company 2: Viessmann Vitodens 100. £4190 (without powerflush, they say it's optional, powerflush would be £480 extra, so a like-for-like quote is £4670)
3) Company 3: Ideal Logic Max 30kW (£3840) or Viessmann Vitodens 100 (£4080), with chemical flush

So the bigger companies are pretty comparable, only the potentially smaller one is notably more expensive (~ £600).

I'm not sure about which boiler to take:
- Viessmann is praised for their stainless steal heat exchanger which seems to work efficiently for longer (aluminium corroding faster)
- The fourth company mentioned "Baxi" which I haven't heard of before who seem to have large-diameter heat exchangers which don't clog up so easily
- Ideal seems to be ideal (pardon the pun) for getting spare parts and are supposedly easy to deal with in case of repairs on warranty

One advantage of Company 2 (the more costly smaller one): For the boiler to be fitted into the conservatory, there needs to be a bit of a modification to the conservatory. I could do this myself, but I'm not a builder so I don't like these types of work too much. And I'd need to do it exactly the day before they come. They offered to do that work as well for an extra £190 (which I think would be a very fair price).

I presume some form of flush is advisable, right? To note, the heating system works fine, we don't have cold radiators, low flow or anything like this. I think the whole central heating system is less than 20 years old.

Are there any aspects I should consider / think of? Any recommendations for a company, or something to look out for?

Best wishes,

Andre

andre_xs

I just realised, is it common to negotiate a little bit? For example, approaching the more expensive company 2 and telling them something like "We had 2 other quotes in the range of £4080 for the same work you are asking £4670 for. We would really like to employ you, is there anything you could do to the price?".

FreeBear

Went through the same exercise myself earlier in the year. Vaillant was an early contender, but quickly got ruled out as it doesn't support OpenTherm - OT is important to me as there is a wider range of smart controls that I can plug in. You may be happy with Vaillant's controls, but be prepared for a shock if they ever need to be replaced.

Baxi have been around for a very long time - They probably manufactured 80% of the back boilers installed during the 70s/80s/90s. Perhaps worth a look, especially if price is a concern. Baxi do both a budget range as well as a more "up market" series.

I'm reasonably happy with my Veissmann and wouldn't hesitate to recommend it - Got a few niggles about OpenTherm compatibility (not all commands appear to be supported). Also don't have any experience of warranty support, and I'm hoping not to need it.

At the end of the day, price, length of warranty, and servicing costs should be the deciding factors. Just a little surprised no one quoted for a Worcester Bosch...

Albermarle

andre_xs said:

I just realised, is it common to negotiate a little bit? For example, approaching the more expensive company 2 and telling them something like "We had 2 other quotes in the range of £4080 for the same work you are asking £4670 for. We would really like to employ you, is there anything you could do to the price?".

One well known negotiating technique ( not necessarily just with heating engineers) is not to just focus on trying to batter down the headline price. For example with Company 1 you could say you only accept the lower figure, and with 2) you could ask for the Powerflush to be included in the £4190 and with 3) you could ask for the Veissman boiler for the price of the Ideal one.
For sure you will not offend them by asking. Also try and find out when they might be available to do the job.

andre_xs

Thanks for the comments. Yes, I forgot to mention these things as well: They have roughly same lead time, and they all offer 10 years guarantee (something I asked for), and yearly inspection is usually £100 +/- £20

Thanks for the negotiating tip ;-)

FreeBear

FreeBear said: You may be happy with Vaillant's controls, but be prepared for a shock if they ever need to be replaced.

Found out today that Tado V3 claims to be compatible with the current Vaillant boilers - Great if you want an off the shelf solution. Still not good if you want to roll your own control system.

MikeJXE

What area do you live ?

My son (gas safe engineer) installs boilers all the time and his rates are no where near those (Leicestershire)

He installs a lot of Ideal, he recommends them as the have a long warranty and his customers often ask for that make as recommended by neighbours 

ComicGeek

You've potentially got 3 different combi sizes there, depending on which Viessmann model is specified.

Most important thing is to work out which size you need, not just what someone wants to fit for you. Flow rate from a 25 kW Vaillant is going to be pretty low!

FreeBear

ComicGeek said:

You've potentially got 3 different combi sizes there, depending on which Viessmann model is specified.

When looking at the boiler specifications, do pay attention to the modulation range and the minimum heat output to the CH system. Also compare DHW flow rates, but do watch out for different quoted temperature rises - Viessmann give a flow rate based on a 30°C rise, whilst Vaillant use 35°C (more on that in a sec).

As mentioned in an earlier post, I'm reasonably happy with my Viessmann 050 30KW - it will modulate down to just 3.2KW from 25KW for central heating. The heating system has only kicked in a few times over the last week (still trying to tune it), from an initial high of ~32%, it has been dropping down to ~12% as the temperature in the house rises - So roughly 8KW down to 3.2KW. If it wasn't able to modulate down so low, I would expect the boiler to start short cycling (not good).

On paper, with a 10l/min cold water flow rate, a 25KW boiler would probably have been fine. Indeed, during the summer months, it was running at ~60% capacity to heat the water to 45°C. Now that the water temperature has dropped, the boiler is running at around 90% (same flow, same target temperature). On that basis, the 30KW was probably the right choice. I note that Vailant have a line of small print to say that a flow restrictor is fitted to achieve a 42°C rise.

Both the Vailant and Viessmann 100 modulate down to around 5-6KW - If you have a lot of radiator, this may be OK. But as the TRVs kick in the heat demand will reduce, and you'll find the boiler short cycling.

[edit - The latest Viessmann 100 will actually modulate down to 3.2KW]

Do have a look at the Viessmann 050 - The modulation range is good, and it is also slightly smaller that the 100(an advantage if you want to put it in a cupboard). Cheaper as well - Had mine installed for ~£2500.

andre_xs

Thanks again for all the input.

- We're London area, and it's not only fitting, but also moving to a new place

- We don't have Smart Home (and don't plan to get it), so those features are not relevant to us

- Regarding minimum heat output, thanks for the tip. I've checked, the Viessmann Vitodens 100-W has an output range of 3.2 kW to 32kW, the Vaillant has indeed 5.3kW (825) or 6.3 kW (830) minimum output.

- I think I'll indeed go for a 30kW range boiler

Another thing I came across a couple of times, does Outdoor Temperature Sensor (weather compensation) make sense for the south of the UK with this rather non-extreme temperatures?

Best wishes,

Andre

FreeBear

andre_xs said: - Regarding minimum heat output, thanks for the tip. I've checked, the Viessmann Vitodens 100-W has an output range of 3.2 kW to 32kW, the Vaillant has indeed 5.3kW (825) or 6.3 kW (830) minimum output.

Another thing I came across a couple of times, does Outdoor Temperature Sensor (weather compensation) make sense for the south of the UK with this rather non-extreme temperatures?

My mistake regarding the output range of the Viessmann - The danger of just grabbing the first spec sheet that turns up without checking the date.. Even with the 100 modulating down to 3.2KW, I still think the 050 is better value.

Enabling weather compensation means that the flow temperature increases as the external temperature drops. Not entirely convinced that it is needed. But I have a temperature sensor outside, so could emulate weather compensation with the home automation system.