Replacement Boiler

[sosborne76]

I need to get a new boiler as my existing one is over ten years old and has developed yet another problem. And given I am renting out my flat I need something that is reliable, besides I will probably be selling my flat in a couple of years.

I have a 2 bedroom flat with one bathroom that has a shower. I have had three quotes with wildly varying results. Firstly two of the fitters have told me a 24Kw boiler would be insufficient to the needs of the property especially in the winter so I looked at 28kw and 31kw models. Another told me that boilers of that power would be overkill and 24kw would be more like it. So what do I need for the property, I was thinking 28ish but this last quote has contradicted?

The models I have been looking at are the Potterton Gold 28, Vaillant Ecotec Plus 31, Worcester Bosch 27 CDi and Worcester Bosch Greenstar Jr 24. On Which's website the Potterton and Vaillant seem like good models with the Worcesters being more average especially on efficiency. And it seems each fitter has preference with two recommending Worcesters (27CDi and Jr 24) and one Vaillant ecoTec plus 31. From what I can tell Worcester have a good rep for support and Potterton not so good, is this the case, and what are Vaillant like?

The prices have all come back in the 1900 bracket so there doesn't seem to be much in it, apart from one guy who said he could a Potterton for 1660. One of the fitters was Worcester Bosch approved so I would get a 5 year warranty apparently, although this one was the guy recommending the 24kw Jr for 1950. Basically a cheaper boiler at a similar price. And when I asked for prices whilst on the phone to him for the Potterton and Vaillant he said he could do it for the same without really looking it up or anything. I maybe tempted to pay more for the longer guarantee but I don't have confidence in them at his point.

To be honest as time progresses I feel like I am more confused rather than getting closer to a decision. I don't know what power boiler I really need. What manufacturer/model is better? What manufacturer support is like? I know these things are never straightforward but I don't even feel in a position to compare plus points and negatives with contradictory info.

Any help/advice is welcome.

 

[petit_pablo]

Potterton is a good buget boiler
Avoid worcester junior but the CDi is a decent boiler
Vaillant is probably best boiler on list.

Go at least 28kw if running a shower ideally. If they are all around the £1900 mark, have the vaillant

 

[ianniann]

Doesn't inspire confidence, does it? I'm struggling to imagine a two bed flat that couldn't be heating to a furnace temperature by a 24kW boiler. For many years I heated a 5-bed detached house with a boiler that output 20kW. You of course have a very simple yardstick. If the existing boiler is adequate to heat the flat, then any new boiler with same output will be plenty. The old boiler is almost certainly 20% less efficient and probably not even working to spec any more.

Since you're fitting a combi to supply the shower, the only thing that really matters is the level of hot water it can provide. These days, 24kW is considered minimal for running a shower, although again I found a 20kW boiler adequate for a shower if not exactly stunning. A more powerful boiler will allow stronger shower at the same temperature, but you'll have to check the mains pressure to see whether that is even possible. If your mains can only push say 8l/min through the shower then there isn't much point buying a boiler that can heat twice that amount to shower temperature. A bath would fill quicker, but it will still fill either way.

A long warranty is always tempting. You need t have the boiler service every year without fail but then you'll presumably have to do that anyway as a landlord. I also think its a good idea to install whatever the guy recommends since that's what he'll be used to installing. Of course you also should pick the guy you have most confidence in

Do you actually care that much about buying a top class boiler that will last forever? Cynical I know, but getting one that will function until you sell the flat seems to be the only goal. The 27CDi is almost a completely different boiler to the Junior, considered much higher quality and certainly with several extra useful features (modulating pump, separate water and heating controls, etc.). The CDi range claims "fully condensing in DHW mode". Anyone know how it does that with essentially the same setup as the Junior? Different primary heat exchanger, but what's so different that they consider one doesn't condense on DHW and the other does?

 

[Tibbot]

The CDi range claims "fully condensing in DHW mode". Anyone know how it does that with essentially the same setup as the Junior? Different primary heat exchanger, but what's so different that they consider one doesn't condense on DHW and the other does?

The old Greenstar had a double pass DHW heat exchanger which is how it condensed in HW. The CDi may have that too. The Junior won't.

The OP could try an installer that does their own back up. In which case even if they specialise in the less known you could get better service than from those who point you to the manufacturer or BG when it goes wrong.

 

[sosborne76]

I am not massively bothered about getting a boiler that will last forever, but I would pay slightly more for a boiler if it was a better model or a more reliable one. Besides I don't exactly know how long I will continue to rent the place and a boiler with warranty will look better to prospective buyers.

It still seems that there are two sides to the 24/28kw argument. The 28kw seems desirable to provide stronger shower flow and a bit of leeway especially in winter. But 24kw is adequate for heating. One of the installers said that it was bad to have a 28kw in such a property that it would actually be inefficient or something?

 

[ianniann]

One of the installers said that it was bad to have a 28kw in such a property that it would actually be inefficient or something?

Potentially. Over-sized boilers are more likely to run outside their best efficiency range, and to cycle on and off.

All the boilers you mention can modulate down to approximately a third of their maximum output, which gives them considerable leeway. Even so, if your flat is even moderately well insulated then you will need less than the lowest modulation of the 24kW for much of the time. Combis are nearly always over-sized and incorporate features so that this isn't a big problem. Powerful combis in small properties tend to be massively over-sized which can lose you a few percent of efficiency. Plus people who eat, drink, and breathe gas panic about them when they aren't running in an optimal setup. A heat requirements calculation for your flat will give a better idea of where the line between "over-sized" and "massively over-sized" is for your flat.

 

[Agile]

All modern boilers are efficient so forget about that.

A combi is rated on the hot water output. Your flat only needs about 6-8 kW heating output.

I would suggest a Viessmann as it has a five year warrantee and the latest design seens very reliable.

A minimum 28 kW is a good idea as a minimum powerfor a combi.

Any competent installer should be able to quote you for fitting any make of boiler although many like to stick to those they know or get the best discounts.

A long warrantee means an extra selling point which might make a difference to a purchasor.

Tony

 

[D_Hailsham]

A heat requirements calculation for your flat will give a better idea of where the line between "over-sized" and "massively over-sized" is for your flat.

Boiler Size Calculator will do this for you.

As for the Hot Water side, measure the cold water flow rate at the kitchen sink. You can do this with a plastic bucket (most have litre marks on the inside) and a watch. Multiply the flow rate in litres/min by 2.5 to find the hot water requirement. This will give a temperature rise of 35C, which is usually adequate. A bigger boiler will give a higher temperature rise, it will not give a faster flow rate.

Assuming the maximum heating output of the boiler is above the heating requirement, you need to check that the minimum heating output of the boiler is lower than the requirement. The lower the minimum is compared to the requirement, the better.

 

[tryitandsee]

Being a full time Landlord, I have installed three Potterton Gold 24HE combi boilers, been in two years, no trouble at all. Tenants have said what great showers they are.

National paper advert £629 24 HE, £689 28HE and £749 33HE.

I would go for either the 24 or 28.

 

[hammerswinger]

I've seen that advert also, (boiler-sales.co.uk) they are selling the Potterton Gold range cheaper than the Potterton Promax range, although the boilers are exactly the same the Gold has a 2 year warranty where as the Promax only has 1 year..... so it's a no brainer.


Cheers.

 

[transam]

The way I see it O.P, ask not what your country can do for u , but what can u do for your country, in these time.s of economic turmoil , buy a boiler made in the U.K , british manufacturing + british job's , u know it make's sense