Help choosing a replacement boiler

[biccy]

Hello group,

Am looking at replacing an old Baxi solo 60 wall mounted boiler that feeds a vented indirect CH/HW system. We want to re-site the new boiler to get it nearer the gas supply and away from the back yard - flue outlet stinks and we have small child.

We also want to add two new radiators to warm a couple of cold spots (half-landing and utility room) and - hopefully - get the house warmer this winter (solid brick victorian semi that gets rather cold this time of year even with heating on).

A friendly local plumber has recommended upgrading to a condensing combi boiler and ripping out the HW tank, feed tanks and associated gubbins. He has recommended installing the Baxi 105e instant or a Halstead ACE 30 boiler and doing all the plumbing and removal of old stuff for =A31750 inclusive.

I have a few questions:

(1) Although these seem like good efficient boilers (90%+) we like to have both bath and shower (small child) as well as wash lots of dirty kiddie clothes so are combis really up to the job or should we just be upgrading the current boiler for a condensing version and leving the HW tank in place ?

(2) I haven't heard of Halstead although they do seem to offer 2 yr warranty and appear high up the SEBDUK listings - is this a good sign of reliable and efficient boilers ?

(3) Would anyone recommend better boilers for the job and is =A31750 a little steep for the boiler, some piping (we are supplying the rads) and about 1.5 days of labour for 2 men ?

hoping I can get some answers (if not all) as we have to decide in a week or so.

Many thanks,

Mark.

[Andy]

Am looking at replacing an old Baxi solo 60 wall mounted boiler that feeds a vented indirect CH/HW system. We want to re-site the new boiler to get it nearer the gas supply and away from the back yard - flue outlet stinks and we have small child.

We also want to add two new radiators to warm a couple of cold spots (half-landing and utility room) and - hopefully - get the house warmer this winter (solid brick victorian semi that gets rather cold this time of year even with heating on).

A friendly local plumber has recommended upgrading to a condensing combi boiler and ripping out the HW tank, feed tanks and associated gubbins. He has recommended installing the Baxi 105e instant or a Halstead ACE 30 boiler and doing all the plumbing and removal of old stuff for £1750 inclusive.

I have a few questions:

(1) Although these seem like good efficient boilers (90%+) we like to have both bath and shower (small child) as well as wash lots of dirty kiddie clothes so are combis really up to the job or should we just be upgrading the current boiler for a condensing version and leving the HW tank in place ?

(2) I haven't heard of Halstead although they do seem to offer 2 yr warranty and appear high up the SEBDUK listings - is this a good sign of reliable and efficient boilers ?

(3) Would anyone recommend better boilers for the job and is £1750 a little steep for the boiler, some piping (we are supplying the rads) and about 1.5 days of labour for 2 men ?

hoping I can get some answers (if not all) as we have to decide in a week or so.

Many thanks,

Mark.

The combi versus boiler+hot water tank argument rages all the time on this NG. The advantages are limitless hot water, no space taken up by tanks etc and mains pressure hot water, but when someone turns on the HW in the kitchen the shower can run cool.

The disadvantages are no airing cupboard, flow rates below what can be achieved with stored hot water and the loss of all hot water if the combi goes down ( with a tank you can have a standby immersion heater available ).

There are hybrid solutions but I expect you don't want to get too complicated.

First off you need decent mains pressure, a flowrate at the kitchen cold tap of 20 litres/min or very nearly is often mentioned.

Second you can avoid the cold shower syndrome ( if you live in a busy household ) by having a pressure equalisation valve put in on the shower feed.

As for baths, showers and washing clothes you can do all of this with a combi but not necessarily at the same time. If you have only one bathroom you're OK.

Some people gripe about it taking 10-15 minutes to run off a bath with a combi, others don't care or get in after five minutes so they can adjust the temperature as it heats up.

The actual time it takes to fill a bath, and the flowrate achievable on a shower depend on the power rating of the combi. 24kW is at tle low power end, 28kW is medium and 30-35kW is high power. I'd go for at least 28kW for a half-decent shower in winter ( much better than electric ) but others will beg to differ.

As for the Halstead and Baxi, I expect they're efficient, as they are condensers, but the SEDBUK rating does not indicate reliability. I've only heard anecdotal stuff about these makes but I don't think they're synomyous with quality, I think the Halstead certainly is a fairly cheap make. If you go back through the uk.d-i-y archives ( use Google Groups ) you will find many a thread on this subject.

I'm not sure about the price, its not outlandish but it could be a little high,

Andy.

[Dave Plowman (News)]

If you're happy with the present performance of your storage system, yes. A normal sized combi simply won't get near it. I'm really not sure why many plumbers insist on recommending ripping out such things - perhaps just to bump up the bill. Or they get more incentives on combis.

[David Hansen]

On 12 Nov 2006 07:08:32 -0800 someone who may be "biccy" wrote this:-

Use a search engine on this group and you will find endless recent discussion about some of what you ask.

However, do consider a few things:

1) Economy in water heating is helped by having the souce(s) of hot water closest to where it is used the most. This minimises the heat (and water) "lost" in long pipe runs.

2) Typically the most used tap is in the kitchen, thus a source of hot water near this is ideal.

3) If there is a boiler in the kitchen but no a hot water cylinder nearby then there advantages in replacing the boiler with a combination boiler and using this to feed the kitchen hot tap.

4) If there is space for a hot water cylinder or thermal store nearby then there is little advantage in the combination boiler. Minimising the pipe run between boiler and cylinder/store increases water heating efficiency, especially id the boiler is used to heat water in summer.

5) Like everything, combination boilers have strengths and weaknesses. Some claim they are the solution to all problems, but they are not.

Without more information people can only make general points. Are the bath and shower in the same room? What sort of shower? Assuming a hot and cold fill washing machine, are clothes washed at the same time as baths/showers are taken? Where is the current hot water cylinder in relation to the hot water outlets? How well insulated is the current hot water cylinder? How much change do you wish to have to your current system?

[David Hansen]

On Sun, 12 Nov 2006 15:50:28 +0000 (GMT) someone who may be "Dave Plowman (News)" wrote this:-

I think it's partly fashion. Also some faults with badly designed gravity hot water systems can be overcome by mains pressure hot water systems. A mains pressure cylinder or thermal store are relatively expensive ways of getting mains pressure hot water, a combination boiler is relatively cheap and involves relatively few changes to pipework (it should involve more changes to the pipework but many don't bother and householders tend to be none the wiser.

[biccy]

Some great responses - many thanks.

To answer some of the questions raised:

The boiler is in the kitchen but the HW cylinder, pump and 3-way valve are in our bedroom (hidden in the wardrobes) which is some 30 feet away. I guess we lose lots of heat in those 22mm pipe runs as the landing is always warm and the cats sleep there a lot:-)

Bathroom as shower and bath and is rigt next to the bedroom so little heat loss there.

Our current heating bills are pretty high (=A360 per month for gas alone) so either the boiler is inefficent (likely) or we simply do not have enough power in the system to heat the fabric well enough to stop it cycling (which it seems to do quite a lot).

I have wondered if it would be easier just to move the boiler to be nearer the HW cylinder (we ave a utility room underneath the bathroom) and change it to be a condensing one but still stay vented....I would hope that the massive increase in efficiency should reduce my bills considerably ???

thanks for the responses so far - I'm fine with vented systems but new to combis and condensing so this is a good group to search.

Mark

[David Hansen]

On 12 Nov 2006 10:43:03 -0800 someone who may be "biccy" wrote this:-

If you do nothing else to the pipework it would be well worth going to some effort to insulate these pipes.

As the shower and bath are together then they are not going to be used simultaneously. That means the reduction in flow when more than one outlet is being used on a combination boiler is not as much of a problem as it would be if they are separate.

If it is cycling a lot than that implies that you probably have too much power and/or it is not being controlled properly. Have you done a heat loss calculation? How does this compare to the boiler power?

It would increase efficiency somewhat, though you would still have a long dead-leg to the kitchen hot tap. However, big reductions in bills tend to come from better insulation. Is the loft insulated properly? What sort of windows do you have?

[John Rumm]

There is no reason that a flue on a modern boiler ought to stink as such

- it might indicate that your current one is not burning cleanly though.

Something else to note is that the new boiler will cause a certain amount of pluming (i.e. visible water vapour in the flue gasses). You may want to site this so as not to be to distracting.

Why not do both? Have the combi and pipe its hot water output to the shower, and kitchen, but keep the cylinder for feeding the bath. That way you can have main pressure water for the shower, and potable hot water in the kitchen, plus a decent flow rate to the bath. If you want to make a change to the cylinder as well then you could replace it with a fast recovery one. That would let you fill another bath within 20 mins of the first one.

They are cheap (wickes flog lots of them)... not high end boilers, but then again not the worst either.

£1750 seems about par for the course... If you are planing to stay in the house for a bit then, personally I would go for a more up market boiler.

[John Rumm]

The heat loss matters in the summer when you will be heating the house needlessly. However in the winter it does not matter since it is just less heat that you need to provide through the rads.

Excessive cycling is more a sign of it being too powerful rather than not enough. A modern replacement will have a modulating burner anyway which will better match the actual power produced to the demands of the house. It may be your rads are undersized (or the system has not been balanced correctly[1]. If the rads are undersized then this will become more of a problem with a condensing boiler which will work more efficiently at lower flow temperatures. You may in that case want to consider moving some rads about and/or adding more powerful ones. Swapping a single panel rad for a double etc is often a low disruption way to do this.

[1] insulation however may make a big difference to fuel bills.

According to the SEDBUK database your current boiler is not far off 80% efficient as it is. So a new one ought to save some money - but not that much on its own (10-15% reduction perhaps). Upgrading to a programmable stat, fitting TRVs to all rads bar one (if not already the case) may yield you some further savings.

Insulating to a reasonable standard and draft proofing where you can will also help.

For some background on sealed systems have a look at the FAQ:

may find the boiler choice FAQ helpful as well:

[Doctor Drivel]

Am looking at replacing an old Baxi solo 60 wall mounted boiler that feeds a vented indirect CH/HW system. We want to re-site the new boiler to get it nearer the gas supply and away from the back yard - flue outlet stinks and we have small child.

We also want to add two new radiators to warm a couple of cold spots (half-landing and utility room) and - hopefully - get the house warmer this winter (solid brick victorian semi that gets rather cold this time of year even with heating on).

A friendly local plumber has recommended upgrading to a condensing combi boiler and ripping out the HW tank, feed tanks and associated gubbins. He has recommended installing the Baxi 105e instant or a Halstead ACE 30 boiler and doing all the plumbing and removal of old stuff for £1750 inclusive.

I have a few questions:

(1) Although these seem like good efficient boilers (90%+) we like to have both bath and shower (small child) as well as wash lots of dirty kiddie clothes so are combis really up to the job or should we just be upgrading the current boiler for a condensing version and leving the HW tank in place ?

[David Hansen]

On Sun, 12 Nov 2006 20:39:03 +0000 someone who may be John Rumm wrote this:-

Only up to a point. If the floor is ventilated, which I hope it is, then some of that heat will be used to try and heat up the countryside rather than the house. Better to heat the occupied part of the house directly.

[Ed Sirett]

Mainly there is less work involved. So the fixed price traders wish to go that way. The main areas where a stored water system take more installation are the Zone valves and control wiring.

[Dave Plowman (News)]

Yehbut even when these already exist and are working properly I'm heard of it recommended they're ripped out and a combi fitted. And not just by dribble.

[Ed Sirett]

Some customers have lived with truly dire conventional setups and have become combi fanatics (which whilst not as good as a stored system can be, it was much better than anything _they_ had previously had). They will even go as far as to remove a good existing conventional system as part of a program of 'updating'.

Some installers are frankly not up to sorting out the S-plan and Y-plan controls, sad but true.

Some installers probably confuse the benefits of going to a sealed primary system with a change over to a combi boiler, believing wrongly that only combi boilers offer this benefit.

[Doctor Drivel]

When they see the space in the airing cupboard where they had a small boiler room, they are usually sold. Then when they have endless showers at high pressure they are hooked. Many have the attitude that even if they have to replace the combi every 8 to 10 years it is worth it.

Fiends of mine approached me a few weeks back. They have a cylinder with two

11" immersions, one top one bottom, both on the side. The top is economy for sinks only the bottom is for the bath, with a nice switch on the wall. The bottom one had gone. I looked at it and saw the hardened jointing paste on the immersion and said I would be surprised if I could get the immersion heater out after 30 years. I couldn't it was seized. A new cylinder then. The cost of an identical cylinder was very expensive as it was not run of the mill. Even standard cylinders are now around £200 without fittings.

I know he detested the tank in the loft as it got in the way. He also didn't like the cylinder taking up space too. His house is a three floor town house with garage on the ground floor, heated by forced air which they love. One bathroom two showers. I suggested they spend some extra and go for a high water flow Rinnai multi-point in the loft on the gable end. They said yes, seeing the benefits of space saved and long showers. They get annoyed when the cylinder runs out of hot water when showering which happened far too often for them and in the mornings as the immersion does not recover fast enough when consecutive showers are taken.

I fitted the Rinnai last week with a flow switch in the cold supply, and the room stat of the forced air heater run through the switch, so when DHW is called by the Rinnai the air unit is switched out as the gas meter is not big enough. The air unit is a convential flue job, with asiomple gas multifunction control. The whole job took less than a day to do.

What happy bunnies. They rave over the mains pressure showers and the space they have gained. Two showers can be had whereas before they could not have two together only one with big gaps between. Now they have showers for as long as they want when they want. The bath fills up as fast as before too.

They like the idea that the DHW temperature can be controlled by a waterproof remote temperature controller. They never went for it, but is can be easily fitted after. So you can lay in the bath and control the temperature of running hot tap. The Rinnai can have up to four of these.

They also like the idea of lower electricity bills too. I reckon they paid an extra £400 over and above a straight cylinder change which would have put them back to stage one. A small price for the great gains.

They see getting rid of a tank and cylinder as being space age.