New boiler to replace Worcester

FreeBear

The Alpha E-Tec Plus NX 28kW has a minimum heat output of 4.3kW. Reasonable but not that low. If you compare the to a WB 4000 or 8000, that will go down to ~3.2kW (from memory). The Viessmann 050 will certainly go to 3.2kW. Both the WB and Viessmann boilers can be had with 10 year warranties (perhaps even 12 subject to certain conditions, as is 10 year warranties).

Why worry about minimum outputs ?

If you use smart(er) controls that can take full advantage of the boiler's modulation characteristics, the boiler output will reduce heat output to match demand. Most houses in the UK only need 6-8kW to raise the temperature, and perhaps as little as ~3kW to maintain it. If the boiler will only go down to say 5kW, it will spend a lot of time short cycling which is bad for efficiency and reliability.

The Alpha will modulate down to 4.3kW, and has the advantage of being OpenTherm compatible (gives you a much wider selection of smart thermostats). A 10 year warranty, with options to extend to 13 years. Price isn't too bad when compared to WB 8000. But do insist that it is supplied with a decent smart OpenTherm thermostat. Digging in to the Alpha specs, it has a pump setting that varies the speed to maintain a constant °C difference between flow & return - Not seen that on a pump before now. Installation manual is very light on details though.

Another change is to swap out radiators for larger ones all round - This allows you to run at a lower flow temperature which in turn means better efficiency from the boiler (and no plumes of white "smoke" out of the flue). I have a Viessmann 050 along with bigger radiators and will typically get 94% efficiency (have a meter attached to the flow/return pipes to monitor output). In this late 1920s 3 bed semi, boiler output averaged 5kWh to heat the place up at 1°C per hour. Will peak at 7kW, and drop to 3-4kW. So for me, minimum output is an important factor. With the smart control system I have, settings are pretty much dialed in to maximise efficiency and comfort.

One last thing - Have you considered a heat pump ?

knightstyle

When you get the new boiler make sure the fitter is registered with the maker and gas safe. Then you will get the long guarantee, probably 10 years otherwise you may like us only get a 3 year g'tee with WB.

Albermarle

https://forums.moneysavingexpert.com/discussion/comment/82002065#Comment_82002065

The basics of a gas condensing boiler have not changed that much. A new equivalent boiler may save you at best a £100 a year in gas, whilst costing £3000……

As suggested a good enhanced service with some replacement parts, would seem a better option.

FreeBear

https://forums.moneysavingexpert.com/discussion/comment/82002257#Comment_82002257

Perhaps not even £100. Assume the old boiler is 85% efficient and annual consumption is 8,000kWh. That would return 6800kWh of heat. If the new boiler is 90% efficient (SEDBUK 2009 rating), that would consume 7556kWh of gas for the same heat. A saving of just 444kWh or about £25 per year. If efficiency could be boosted to 94%, that would increase the saving to about £43 per year. If the old boiler had been something like a Baxi back boiler such as I had (efficiency rating of ~72%), £100 per year based on 8000kWh consumption wouldn't be far off the mark - I only replaced the Baxi because Cadnet had slapped a "Do not use" notice on it.

But fitting smart(er) controls and turning the flow temperature down to say 60°C, the OP could still save 5-10%.

WIAWSNB

If it ain't broke, don't fix it.

If it is broke, then just fix it if you can.

When it's genuinely beyond eco repair, then replace it... 😁

yomagsy

https://forums.moneysavingexpert.com/discussion/comment/82002103#Comment_82002103

Some good ideas in your response and I do enjoy life. But if I have a major boiler breakdown in winter, I certainly won't enjoy life. Have fun yourself :)

yomagsy

https://forums.moneysavingexpert.com/discussion/comment/82002522#Comment_82002522

I had a do not use notice on mine 15 years ago so had no heating or hot water, in November. Luckily I had a good neighbour who let me in to keep warm and shower but not a scenario I want to repeat. As I said previously, I have had 4 leaks and an expansion tank fitted in the last 4 years so don't trust it now. I lowered the temp years ago to save money and that has worked well. The boilers I am looking to replace it with have 10 year warranties so I should have peace of mind for a while. Thanks for your response

yomagsy

https://forums.moneysavingexpert.com/discussion/comment/82002103#Comment_82002103

Love your words about Trigger's brush HAHA. I started this search because my upstairs rads are suddenly not getting warm when the downstairs ones are hot. Yes they have been bled, yes they have been turned up but not good so like the time my 18 year old car started with problems that would be expensive, it's time to look for a replacement I think.

FreeBear

I started this search because my upstairs rads are suddenly not getting warm when the downstairs ones are hot.

Assuming no one has been messing with the lockshield valves, it could be the TRV valves upstairs stuck in the closed position - I'm assuming TRVs are fitted all round. A little squirt of a silicone lubricant (not WD-40) on the TRV pins may help. You'll need to unscrew the TRV head to gain access to the pin.

Or it could be as simple as someone turning the TRVs down to minimum and you haven't spotted it yet.

yomagsy

https://forums.moneysavingexpert.com/discussion/comment/82002775#Comment_82002775

I hope nobody has been messing with the TRVs; I live alone ! he he ! I've turned them all up to max again, bled them all again (no air) and will see what happens when they come on in the morning. Thanks