Gas boiler upgrade - Ideal boilers - opinions please

2011

I will start by saying that I am am amateur plumber. I know what I don't know and when it is time to call in an expert.
Now is that time

So I have a 20 kW Vokera Mynute system gas boiler in my 4 bed house at present. It never worked well. No matter how long I ran it for even with the DHW zone valve off the house would never get very warm. Rads would never get very hot unless I turned all / most rads off then I could get an individual rad hot.

My plan is to upgrade the boiler. A local RGI popped out and is suggesting replacing my boiler with an Ideal system boiler, I think he said 24 kW. I am not familiar with this brand. He is recommending a magnetic filter.

Will this make a big difference in terms of bills and heat output?
Is this a good brand?
What are people's experiences?
Any advice?

Many thanks.

Calahonda52

Sounds like a plumbing issue rather than a boiler issue at this point.
How old is the system
is it open or closed
does it have anti corrosion stuff in it
any air in the system

rads could be full of sludge and IMO under no circumstances should u fit a new boiler without clearing out all the gunge and putting an anti corrosion solution in the system.
(all described in et101-2008 543.1.1.1) .

RebelButtMunch

I had the same problem and a stronger pump fixed it

2011

Calahonda52 wrote: »

Sounds like a plumbing issue rather than a boiler issue at this point.

Maybe.
Plumber couyld not have been worse. Celtic Tiger stuff.
I had to fix countless plumbing issues myself.

How old is the system

About 15 years.

is it open or closed

Open

does it have anti corrosion stuff in it

Yes.

any air in the system

No.
Also it holds pressure a' 1.5 bar well.

rads could be full of sludge and IMO under no circumstances should u fit a new boiler without clearing out all the gunge and putting an anti corrosion solution in the system.

Agreed. RGI said the same.

Thanks for your input.

RebelButtMunch wrote: »

I had the same problem and a stronger pump fixed it

Yes, the new bolier has a more powerful pump.

2011

When I say the system is open, I mean I have a tank in the attic that provides head pressure to the system. Thsi is fed by mains water pressure. The rads and coil in the hot water tank are fed from a closed loop. I keep this at around 1.5 bar. I can repressurise this from the main water supply (3 bar) when required.

John.G

Can you post a photo of your gas meter to see if its suitable for monitoring your boiler output with all rads opened up fully and that will give a better feel for the problem then.

2011

John.G wrote: »

Can you post a photo of your gas meter to see if its suitable for monitoring your boiler output with all rads opened up fully and that will give a better feel for the problem then.

You mean the gas meter in the box outside?

John.G

Yes.

Wearb

2011 wrote: »

Yes, the new boiler has a more powerful pump.

Certainly wouldnt be a reason to change the boiler. Just change the pump, if that's the problem. Is your pump set to its highest setting?


You could test for sludge by just turning on the amount of radiators that the current setting will heat sufficiently,then after they have heated up well, feel the bottom center of each rad to see if there is a cold spot. Then turn those off and the others on and repeat.

Could also be a partially blocked heat exchanger in the boiler, but that would give it's own problems. I only do oil so not familiar with gas boilers.

2011

Wearb wrote: »

Certainly wouldnt be a reason to change the boiler. Just change the pump, if that's the problem.

I never suggested that was why I was replacing the boiler. I was just responding to a question asked. Apart from the fact that ½ of these boilers have expired in my estate (all the same type) it is very low efficiency and most probably under sized. Also replacing the boiler with a superior unit resolved the issue for others in my estate as well as resulting in lower bills.

Is your pump set to its highest setting?

Yes.

You could test for sludge by just turning on the amount of radiators that the current setting will heat sufficiently,then after they have heated up well, feel the bottom center of each rad to see if there is a cold spot. Then turn those off and the others on and repeat.

Could also be a partially blocked heat exchanger in the boiler, but that would give it's own problems. I only do oil so not familiar with gas boilers.

Ok. Thanks

Wearb

If your boiler is continuously running and radiators are not getting to temperature, then it's most likely undersized, but this (unless an extension added) would always have been the case. If its not continuously running at max, then perhaps the circulating pump is weakening. If undersized, then you would always have had a problem. You probably know if the circulator had a run or start capacitor. you could check it to see if it's still good.
20Kw would be enough for a lot of 4 bed houses (unless bigger than average) with good insulation and windows etc.

John.G

A few readings from the gas meter (if suitable) will give the boiler output.

2011

Wearb wrote: »

If your boiler is continuously running and radiators are not getting to temperature, then it's most likely undersized, but this (unless an extension added) would always have been the case.

No extension. Yes it never worked properly.

20Kw would be enough for a lot of 4 bed houses (unless bigger than average) with good insulation and windows etc.

As above the plumber had no idea what he was doing. Either that or he did not care. We had leaks, drains that would only work if water could flow uphill and just generally poor finishes.

Insulation was poorly done but I have addressed this to a large extent. Windows are poor quality and not properly installed but I am addressing this too.

I started this thread primarily to get opinions on the boiler I am considering. Any views on this? Thanks.

Wearb

2011 wrote: »

No extension. Yes it never worked properly.



As above the plumber had no idea what he was doing. Either that or he did not care. We had leaks, drains that would only work if water could flow uphill and just generally poor finishes.

Insulation was poorly done but I have addressed this to a large extent. Windows are poor quality and not properly installed but I am addressing this too.

I started this thread primarily to get opinions on the boiler I am considering. Any views on this? Thanks.

Well now that we've put a bit of meat on this thread, hopefully the gas lads will comment and help you out regarding the new boiler.

You'll need to consider the improvements you are making when deciding on the size of the new boiler.

2011

Wearb wrote: »

You'll need to consider the improvements you are making when deciding on the size of the new boiler.

Absolutely. I will advise the RGI accordingly.

Lenar3556

I am familiar with a large local authority housing upgrade contract which was completed and fitted with some 300 Worcester Bosch gas system boilers in 2012. They have provided excellent service since.

I put in a 30kW model into my own house at the same time. It has never missed a beat since either.

I understand Ideal is a reputable brand too. I would probably go for the Bosch, for no particular reason other than the above experience.

2011

Yes, I believe this is a good boiler. Also offered to me at a higher price but I’m told the Ideal is just as good and shares identical key components. Thoughts?

With a clean heating system the choice of boiler is less important as it’s the water quality that often dictates the lifespan of most boilers, if I had to choose a boiler I would look for one with decent local aftercare and a long warranty, with a zoned heating system I would also if practical look to run two different flow temperatures, a higher one for the hot water cylinder and a lower one for the rad circuit which would also have weather compensation to squeeze that extra bit of efficiency out of the boiler, you can use the satisfied on the cylinder stat to energise your heating wiring or power a switch so the higher hot water temperatures can’t enter the rad circuit when the hot water is calling, having the boiler wired for hot water priority also allows you to fit a smaller output boiler because you don’t add the hot water requirement to your heat load requirements.

WillContribute

Most modern gas boilers are able to modulate (or scale down) their max heat output as required by the system to maintain the output temp. Instead of switching on and off, like an oil burner, they adjust the gas flow level to keep it running steady, rather than on/off. If you buy a slightly bigger output boiler, it can adjust down its output to suit what your house actually needs.

The cost of going bigger is normally not that much more and will give some headroom or security.

Personally, I like Baxi, the have been cheap, robust and parts are readily available, but maybe I am lucky. Bosch are likely a bit better but also more expensive. Anyway, when I was buying a boiler for a new build, A rated house, spoke to a service guy first and he told me, yep the 18kW model should be fine, but the 24kW model was bullet proof, tried and tested slightly older model. I stumped up the extra few Euro for 24kW and no problems in years. Suggest can you find a service guy for your preferred make There are guys out specialising in each manufacturer. .

WillContribute

WillContribute wrote: »

Most modern gas boilers are able to modulate (or scale down) their max heat output as required by the system to maintain the output temp. Instead of switching on and off, like an oil burner, they adjust the gas flow level to keep it running steady, rather than on/off. If you buy a slightly bigger output boiler, it can adjust down its output to suit what your house actually needs.

The cost of going bigger is normally not that much more and will give some headroom or security.

Personally, I like Baxi, the have been cheap, robust and parts are readily available, but maybe I am lucky. Bosch are likely a bit better but also more expensive. Anyway, when I was buying a boiler for a new build, A rated house, spoke to a service guy first and he told me, yep the 18kW model should be fine, but the 24kW model was bullet proof, tried and tested slightly older model. I stumped up the extra few Euro for 24kW and no problems in years. Suggest can you find a service guy for your preferred make There are guys out specialising in each manufacturer. .

Over sizing a boiler can come with its own issues, when choosing a boiler you calculate your heat requirements and fit the boiler that matches that then range rate the output during commissioning, most boilers I see are over sized and have problems with both insufficient gas pressure and kettling when just the hot water is running which can damage the boilers pump.

WillContribute

gary71 wrote: »

Over sizing a boiler can come with its own issues, when choosing a boiler you calculate your heat requirements and fit the boiler that matches that then range rate the output during commissioning, most boilers I see are over sized and have problems with both insufficient gas pressure and kettling when just the hot water is running which can damage the boilers pump.

Agreed, you've got to make sure you don't over cook it. As long as you are reasonable the gas network should supply 30+kW for a domestic @20mBar, can't find the link now but looked it up before, so a reasonable bit more on the boiler over 20kW should be fine unless there is something wrong locally. (Not the customer's issue). Ketting can be an issue, but if it's a modern boiler it should reduce its heat output by reducing gas flow to keep the temperature in line. There might be something else wrong. Maybe be careful to not max out the temp/heat output.

Plan ahead for the extension, we all need it after this year, and also when the wife complains you got a **** boiler you can say you got the next bigger one than recommended for safety. 😠That's worth the bit extra.

2011

gary71 wrote: »

With a clean heating system the choice of boiler is less important as it’s the water quality that often dictates the lifespan of most boilers

The water quality is good. Not acidic and no limescale build up.

if I had to choose a boiler I would look for one with decent local aftercare and a long warranty

Indeed, I am considering both Ideal & Worcester Bosch. However I am leaning towards the Ideal as so far all of my information points to the quality being the same but Ideal is around €400 cheaper. Both have excellent warranty and are supported locally.

with a zoned heating system I would also if practical look to run two different flow temperatures, a higher one for the hot water cylinder and a lower one for the rad circuit which would also have weather compensation to squeeze that extra bit of efficiency out of the boiler

Pretty much done. I have 2 zones:

- Zone 1
This has a Sonoff (smart switch) that controls a zone valve for DHW. The zone valve has an auxiliary contact that fires the boiler when the valve is in the open state. The Sonoff is connected to a temperature sensor that can provide temperature control. Alternatively this zone valve can operate on the Sonoff time clock.

- Zone 2
This has a Sonoff that controls a zone valve for all of my rads. Again the zone valve has an auxiliary contact that fires the boiler when the valve is in the open state. The Sonoff is not connected to a temperature sensor that is generally unable to reach the set point. For this reason weather compensation would bring nothing to the party.

If the house is cold I don't attempt to heat DHW at the same time as rads so that all of the heat output from the boiler is directed to the rads.

2011

WillContribute wrote: »

Most modern gas boilers are able to modulate (or scale down) their max heat output as required by the system to maintain the output temp. Instead of switching on and off, like an oil burner, they adjust the gas flow level to keep it running steady, rather than on/off.

Yes the RGI explained this to me. He said that the pump output could modulate to suit demand. I am open to correction on this but I think that he said that a valve on the output is a modulating control valve (as opposed to an on/off valve).

If you buy a slightly bigger output boiler, it can adjust down its output to suit what your house actually needs.

My understanding is that for maximum efficiency the boiler should be sized to meet the load. My predicament is that I have two RGI's quoting with different opinions:

- RGI #1 suggests 19 or 23 kW boiler
- RGI #2 suggests 24 or 30 kW boiler

There is quite a difference between the extremes!

I would like the RGI that I select to be a little more scientific about sizing the boiler as it would seem to me from my limited knowledge that getting this wrong would have a significant impact on system performance.

The BER rating isn't wonderful. I not sure exactly what it is but my home is a detached 4 bed with 50mm warm board on external walls. Windows are the standard low quality wooden Munster Joinery double glazed units that were installed everywhere in the early naughties. In my opinion Durkan Residential installed the windows and doors very badly without finishing reveals properly and took a lot of short cuts with respect to installing insulation properly. I have insulated the attic well and am upgrading the windows to triple glazed UPVC units and the doors will be composite with a high U value.

The cost of going bigger is normally not that much more and will give some headroom or security.

Yes, for the Ideal I think the difference is €60

Bosch are likely a bit better but also more expensive.

I wouldn't say money is no object but I want this boiler to last a long time and if that means spending a few bob extra I will do that.

There is a installation process for gas boilers that hasn’t changed, you determine your heat load and adjust the boiler to suit, it’s in the interest of the installer to fit a boiler with a badged capacity close to the required output to prevent the issues that can occur with over sizing like insufficient gas or inability to commission correctly.

The idea of letting boilers modulate to compensate for over sizing has become a thing because of sales reps, their selling what they want not what the home owner needs, by believing the hype the installer doesn’t have to take ownership for setting the boiler up allowing them to get in get out quicker.

In the UK the RGI has to do a heat loss calculation to determine the boiler size required because of that 12-18 kw output boilers are being fitted where we are fitting 24-30 which can waste a lot of my time trying to commission them.

I can see the benefit of fitting a larger boiler if a extension is planed in the near future but because this is often done in 1/2 inch there is no point really.

John.G

The minimum output of the boiler should be taken into account as well, unfortunately a lot of manufacturers have the same minimum output for a range of boilers (probably the same burner) from say 30kw down to 18kw, both might have a minimum output of 5/5.5kw which is really poor in these days of zoning and greater insulation, it should be the norm IMO for all boilers to have a modulation ratio of ~ 15:1 to get down to a minimum output of say 2kw as most gas boilers do not like cycling and some can barely deal with it without large extremes of flow/return temperatures. I think Viessman do make one model that has a modulation ratio of 17:1, but is relatively expensive. While gross oversizing is obviously not desirable, the boiler can be range rated, ie its maximum output reduced to suit the heating load but its minimum output cannot be reduced. So wouldn't mind oversizing a little as long as the minimum output is the same as for the calculated rating.

Wearb

Is there much difference in efficiency between a gas boiler firing at max and min when modulating?


With oil there is a difference if fired too low (leaving all the other problems this causes to one side for now). It can be best described as trying to boil a 20 litre saucepan with a candle.

Wearb

Wearb wrote: »

Is there much difference in efficiency between a gas boiler firing at max and min when modulating?


With oil there is a difference if fired too low (leaving all the other problems this causes to one side for now). It can be best described as trying to boil a 20 litre saucepan with a candle.

The max and minimum work together to keep the boiler in its most efficient sweet spot, good system design and external controls makes it easier for the boiler to do its job.

John.G

If talking about combustion efficiency I wouldn't think that there would be much difference as long as the excess air stays constant, see numbers from a friends Vokera mynute below, working perfectly after 8 years.

Oil boilers now have a bigger range with the same burner, ie my 15 year old Firebird (70/90) or 20.5 to 26.4kw come now (in condensing form) rated 50/90) or 14.7/26.4kw, they are factory dispatched at 20.5kw I think but don't know what differences
in combustion efficiency, the lower rating will cycle less often but I was quite surprised to see the very small efficiency differences that cycling in general makes bearing in mind that the boiler does a 12 sec cold air purge and some now a 12 sec after purge.

Vokera Mynute HE (20 KW) Boiler
Combustion Tests. October 2013
Hi Fire/Low Fire
CO2 9%/9%
CO 83/12
Ratio 0.0009/0.0001
O2 5.1%/5.6%
Excess Air 32.6%/36.9%

2011

Thank you all for your input.

Update:
I have decided to replace my olde inefficient boiler with a 24 kW Ideal Logic system boiler. The RGI will flush the system, balance the rads and install a Magnaclean magnetic filter. Total cost of €2k inc VAT, which I think is fair enough.

I will look after the electrical end (in terms of controls).

2011

Job done!

Very professional job, no hiccups.
As expected the new boiler has delivered the desired result. The RGI discovered that the pipe feeding the kitchen rad was partially blocked with Boss White.

DHW heats far quicker and all rads can now get hotter than ever before and at the same time.

Thanks again for all of the advice.

CGI_3

2011 wrote: »

Thank you all for your input.

Update:
I have decided to replace my olde inefficient boiler with a 24 kW Ideal Logic system boiler. The RGI will flush the system, balance the rads and install a Magnaclean magnetic filter. Total cost of €2k inc VAT, which I think is fair enough.

I will look after the electrical end (in terms of controls).

Good price. What part of the country are you in? I'm seeing prices of 2,600 + for what sounds like the same set of circumstances.

Caranica

2011 wrote: »

Job done!

Very professional job, no hiccups.
As expected the new boiler has delivered the desired result. The RGI discovered that the pipe feeding the kitchen rad was partially blocked with Boss White.

DHW heats far quicker and all rads can now get hotter than ever before and at the same time.

Thanks again for all of the advice.

Great to read. I've had a couple of quotes for replacement boilers and Ideal was one of them. €600 cheaper than the Bosch one.

I had a Mynute 16e, and am the last of my neighbours to replace mine (new builds 17 years ago).