Boiler advice needed please

NRGMAN

Finally admitting that it's now time to accept that my 30 years old boiler is not going to see me through another Winter. Therefore, I am looking for combi boiler recommendations for my one bedroom home. Heard great things about Worcester Bosch and have already had a pretty good quote from Boxt for one such boiler (Greenstar 4000).

Open to suggestions/recommendations for boilers anyway so would warmly welcome these, please, as well as any reputable online boiler guide anyone may be aware of too,

Thanks, one and all! 😊

tacpot12

I bought a WB Greenstar 4000 for a rental property I own through Boxt and was very pleased with the service.

QrizB

My previous boiler was a Worcester Bosch, a Greenstar Ri. It lasted from ~2004 to 2025, when it developed a fault and I decided I'd get a replacement rather than trying for a repair.

I ended up choosing a Vaillant simply on price but would have been happy to have another WB.

I got mine via Boxt too. Their engineer (an independent who was working for them) arrived on time, finished early and mostly kept to himself but was friendly and cheerful whenever we interacted.

FreeBear

I went with a Viessmann 050 as I could hook it up to my smart control system. Combined with oversized radiators throughout, is has proved to be fairly efficient (around 92-94%).

But if I were to do it all again, I would give serious consideration to a heat pump - On the right tariff, running costs would be lower than a gas boiler for all but the coldest of days (-10°C or lower).

WIAWSNB

https://forums.moneysavingexpert.com/discussion/6673917/boiler-advice-needed-please

A bit more info on yer home, please.

Is it a house or an apartment/maisonette? Would an ASHP be an option, or are you ruling it out entirely?

How many rooms, and how many rads? And, what power is your existing WB, and are you totally happy with that - ie, shower performance?

Ok, I'm not going to recommend a make, as I'm just not clued up enough with current models. You will, tho', have a good range to choose from, and most/all should be perfectly good and reliable - and that obviously includes WB.

A few things I think you should consider, tho';

1 No idea what your current controls are - room stat and timer - but your new boiler will come with a Prog Stat at least. Do you know what a PS is? The issue is, there are a few different control 'protocols' used by boiler manufacturers, and choosing the ProgStat with the 'correct' protocol will make your boiler behave a tad more efficiently, and also a tad more 'gently'. So, should be better economy, and better longevity. I personally think folk are bonkers if they don't choose a fully compatible control system. The issue then is, some controls are nicer to use than others...

I've seen, and set up, the WB jobbie in a house recently, and was not impressed - it's ugly and basic. But, it should get the best out of the WB. I think that only WB's controls will work fully with WB's boilers, so that would rule out any 'nicer' controls, such as Nest or Hive. I'd ask WB to confirm.

The latest Hive, for example, includes 'Opentherm', and their wee MINI is a sweet unit, but only if you use a Smart phone too. Are you up for 'Smart' controls? They are very intuitive, and a great feature.

2 Any idea what condition the rest of your CH system is in, particularly the rads? Have you bled a rad recently? If so, what colour was the system water? If any rad is dodgy, I suggest you will want to replace it. And if you replace it, then seriously consider going up-sized, such as adding a panel or fins - eg single-panel to double. Double san fins to double with double fins, that sort of stuff.

If you do this in at least the main living/heating areas, you should then be able to turn down your boiler output temp, and still get the same overall heat out of these rads. Benefits; lower rad surface temp. A cooler and hence more efficient boiler. A cooler and hence less stressed boiler.

NRGMAN

https://forums.moneysavingexpert.com/discussion/comment/82048195#Comment_82048195

Thanks to all of you who have responded, very much appreciated.

Ok, WIAWSNB, I can advise it is a one bedroom terraced house on one level. Number of radiators is 6 and in good condition, and bled recently. Water was not discoloured. Each radiator has a thermostatic valve. I don't have a thermostat and the current relic of a boiler is a Sime Friendly. My shower is an electric one.

WIAWSNB

https://forums.moneysavingexpert.com/discussion/comment/82049177#Comment_82049177

Thanks.

Are you happy with your leccy shower? Will you want a 'proper' one at any point - ie powered by the combi?

Are you sure?! 😸

A combi will give you a far superior showering experience, tho' of course you'd need to have a mixer fitted in place of the leccy jobbie.

If you do not want to change the shower, then the smallest combi should do the job easily, say a 24kW jobbie.

WIAWSNB

What do folk think of the more compact and much cheaper boilers such as the WB 1000 instead of the 4000?

I understand they aren't as sophisticated in the modulating department, but what difference would it make in practice?

FreeBear

https://forums.moneysavingexpert.com/discussion/comment/82049382#Comment_82049382

The WB 1000 has a minimum CH output of 5.75kW (with a 50/30°C flow/return). With only 6 radiators, it will be constantly short cycling which would kill any efficiency. The WB 4000 is better in so much as it has a minimum output of 3,2kW.

I have a total of 9 radiators running from a Viessmann 050, which will also modulate down to ~3.2kW. Even with the smart(er) control, I would find that the boiler would short cycle as the thermostat approached the target temperature. The answer (for me) was to introduce a 15 minute delay between a flame off event and another flame on. Coupled with a 0.5°C overshoot, I no longer get any short cycling. Don't think WB has any boiler settings to reduce short cycling, and I suspect their controls don't either. Hive, Tado, and the rest of the secondary market do not support the WB communication protocol (Energy Management System or EMS for short). You might get short cycling under control by using a complete building management system, but an "off the shelf" system is very expensive. The alternative is Home Assistant (other open source systems available) along with a secondary interface for the boiler. Downside to HA is it has a steep learning curve and requires a certain geek orientation.

For a one bed property where hot water demand is just a couple of sinks, I'd be tempted to fit instant water heaters under the counter and retain the electric shower. Then get a small ASHP installed - A 5kW is likely to be bigger than is needed, so maybe a 3.5kW unit would suffice. Either one would easily cope with ticking over at a much lower output than any gas boiler. Should domestic hot water be required rather than instant water heaters, a Heat Geek mini store would be an option - With a one bed property, I'm guessing there isn't space for a full DHW tank.

NRGMAN

https://forums.moneysavingexpert.com/discussion/comment/82049382#Comment_82049382

When I went through the checks process online to arrive at the recommended boiler for my current set-up and needs, the 4000 came up and the quote provided. I had also seen it mentioned prior to that as an excellent, reliable boiler.

As regards the shower, a new electric one was only fitted last year so I'd want to retain it.

WIAWSNB

The 4000 seems to be pretty much the default choice. Really, tho', it should have dedicated WB controls to get the max efficiency out of it. I presume it'll be the smaller 25kW jobbie?

Totally understand you not wanting to replace the shower, but the difference between the two is huge.