New heating system annoyances

[Stotty1]

Hi

We have this last week had a new heating system fitted.
As a quick overview,
We replaced 80% of the radiators, added a small rad to the downstairs WC and replaced all the heating pipe work with 15/22mm copper pipe throughout.
We removed the old Proton conventional boiler and water tank and put the new Worcester Bosch 32cdi combi boiler in the airing cupboard.

Its nice to finally have a warm house but there are a couple of niggling issues I wanted to ask about before I contact the installers and sound stupid.

1. The boiler is in the airing cupboard against our bedroom wall and when its on it sounds like a bus idling, it is not super loud but you can hear it in every room and it is loud enough to stop you getting back to sleep. I'm pretty sure I read beforehand the Worcester Bosch greenstar range is whisper quiet.
I just wondered if anyone else has experience with this boiler and is it normal to make a continuous hum noise when on?

2. We have a tower rail rad in the bathroom and when the heating is on it just seems to continuously tick. I have tried bleeding it but to no avail. Is there a way of stopping this?

3. We have also noticed our gas usage has pretty much doubled since the installation, I thought it with all the new energy efficiency settings on modern boilers it would save gas.

Thanks for any advice that anyone can give.
Carl

 

[muggles]

1. They're not super loud but not the absolute quietest. If noise was going to be a factor in boiler selection, you should have had one with Quiet Mark approval (most Vaillants, Glow-Worms, some Ideals). If it's mounted to a hollow wall, that will act as a sound box and amplify the noise. The only way to fix it in that case is to remove the boiler, strip off the plasterboard, add sound insulation to the wall, re-board (preferably plywood for a stronger boiler fixing) and refit the boiler. Either that or relocate the boiler. Did you mention to the installers that noise should be a consideration when locating the boiler?

2. Towel rads often do that - it's because the metal rail expands at a different rate to the plastic brackets. Try loosening the brackets slightly, or even putting some silicone grease between the bracket and the rail.

3. You've not given any details about your old boiler (you've said Proton, but possibly meant Potterton, but no model given), but it could be that your new one is too powerful for your house even on its lowest output setting. This will cause gas usage to increase. How many radiators do you have? Are they large or small? Modern boilers like large radiators run at a low temperature - that gives best efficiency. If your new boiler is cranked up to maximum temperature and servicing tiny radiators, it'll be no more efficient than your old one.

Some good further reading here on modern boiler efficiency, if you're interested... https://theintergasshop.co.uk/content/187-why-your-new-gas-boiler-isnt-efficient

 

[Stotty1]

Thanks for the reply muggles.

1. It's mounted to some ply wood against a stud wall so it is probably vibration echoing in the wall as you said then.
To be fair I can't remember if I mentioned anything regarding noise levels although I did point out the old tank was very noisy so it would be nice to get rid of it.
So guess we will just have to live with it now.

2. Thanks I will give some silicon a go.

3. Sorry yeah the old boiler was a Potterton Promax SL not sure on the size though.
We have 10 rads in total (a double rad at 1600, 5 single rads between 1000 and 1200, 3 single rads between 600 and 800 all at 600 high and the towel rad at 600 x 1222).
Might be a silly question but they did change the gas pipe from a 15mm to a 22mm pipe not sure if that would make a difference.

Thanks for the link I will give it a look.

 

[fixitflav]

We have also noticed our gas usage has pretty much doubled since the installation, I thought it with all the new energy efficiency settings on modern boilers it would save gas.

Maybe the house, or more of it, is warmer than it was before. Also in the current cold snap gas usage will be above average.

 

[Stotty1]

Maybe the house, or more of it, is warmer than it was before. Also in the current cold snap gas usage will be above average.

The house is definitely warmer than it used to be especially the upstairs as it used to have old 1970's rads in all the bedrooms which seemed to give out little heat.

The old boiler used to run almost continuously during the periods of time it was on, only ever turn off for maybe a couple of minutes here and there as the house would never be warm enough to give it a rest.

I don't really mind paying a bit extra to actually have a warm house i just thought it would have gone the other way as the boiler is now running less.

But as you say the current cold snap doesn't really give a comparable picture.

Thanks for the reply

 

[muggles]

OK, so the maximum load on your boiler when all radiators are turned on full is about 8kW. Your boiler's minimum output is 7.15kW, very close to the maximum your system can absorb. This will lead to boiler cycling, which is inefficient and increases wear & tear. In short, your boiler is too powerful for your heating system for the majority of conditions, which is why it's not very gas efficient.

 

[ericmark]

My father had a new boiler fitted, some government deal so did not cost too much, however the first thing I saw was a power shower connected to a combi boiler which was not just wrong but illegal, and they were called back to correct it, that should have flagged up cowboy.

Then he had problems with living room getting too hot, and sitting room used a bedroom too cold, a quick check and every lock shield valve was wide open, adjusting them did improve things.

Next was the thermostat, originally was hard wired, in the hall, they removed wiring and fitted a wireless Honeywell thermostat, quite good quality, however really too good, it switches off/on as it approached the target temperature to stop it over shooting, but with a modulating boiler that upset the algorithms built into the boiler.

I hunted for a programmable thermostat instead of the programmer and thermostat, however I went cheap and bought a pup, which failed after around 6 months, and it seems you can buy cheap hard wired wall thermostats which don't have anti-hysteresis software and are reliable, but with wireless, very cheap not reliable, and mid range have anti hysteresis software which reduces boiler efficiency. So you need top quality that works out when to switch off, so switches a few times as possible to use wireless. It was an early Worcester Bosch so ebus control was not available for that model. Even when ebus control is available with Worcester Bosch it controls one room only, there does not seem to be the option to use OpenTherm so very limited as to which thermostats can be used.

I used electronic TRV heads, but again got it wrong, seems the make I bought should have worked with Nest, but Nest withdrew support.

When dad died we had to move in with Mum, but we knew at 90 her days were numbered and so did not worry about running costs, knew the control was causing boiler to run inefficiently, but as long as temperatures were OK, didn't care. The electronic heads did cure the temperature control problem.

However our own house the central heating worked, and we never even thought about it, until we moved in with Mother. And what became very apparent it is not just the way the central heating works, but house design, and it is all well and good saying best car is a mini, but that is not the case with a family of 6, and same for heating. It is what suits your house.

The report @muggles has linked to is very good, but the question is what to do to correct, rather than what should have been done, my son tells me the gas bill has reduced a lot since he changed the boiler in my old house, but I had house at 20°C and he has it at 18°C and also fitted new front and back doors. So not a clue really.

 

[Stotty1]

OK, so the maximum load on your boiler when all radiators are turned on full is about 8kW. Your boiler's minimum output is 7.15kW, very close to the maximum your system can absorb. This will lead to boiler cycling, which is inefficient and increases wear & tear. In short, your boiler is too powerful for your heating system for the majority of conditions, which is why it's not very gas efficient.

Interesting, thanks.

I'm not sure why the installation company chose this boiler then, I hoped when they measured up to pick the right rads for each room they would of also worked out the most efficient size boiler. Silly of me to just took there word for it really.

Guessing there is not a lot that I can do now the installation is complete.
Guessing the wear and tear will reduce the life of the boiler though

Interestingly looking back one of the other quotes I got was for an even bigger boiler: Worcester Bosch 35kw Life.

 

[Harry Bloomfield]

2. We have a tower rail rad in the bathroom and when the heating is on it just seems to continuously tick. I have tried bleeding it but to no avail. Is there a way of stopping this?

That will be exasperated by regular heating up and cooling, as the boiler fires up and shuts down.

3. We have also noticed our gas usage has pretty much doubled since the installation, I thought it with all the new energy efficiency settings on modern boilers it would save gas.

Have you the Worcester specific control kit installed, or are you using older, more basic on/off control? The proper kit will anticipate the need for the boiler to begin to back down its output, reduce gas consumption, reduce the heating / cooling ticking and maintain a more stable temperature.

 

[Harry Bloomfield]

Interesting, thanks.

I'm not sure why the installation company chose this boiler then, I hoped when they measured up to pick the right rads for each room they would of also worked out the most efficient size boiler. Silly of me to just took there word for it really.

Maybe it is that Kw capacity, to meet the demands of two bathrooms. In a combi, the hot water demand usually sets the size of boiler needed.

 

[muggles]

Combi boilers are specified for hot water output generally, rather than heating, but they are able to vary their heat output to the radiators via a process called modulation. Your boiler's maximum heat output to the radiators is 24kW, minimum is 7, giving you a modulation ratio of 3½:1 (WB would argue it'sactually 4½:1 as your hot water output is 32kW). That's fairly poor by modern boiler standards - many can now achieve 10:1, so a 32kW boiler would be able to reduce to 3.2kW, making it much more suitable for smaller systems.

Had you gone for the 35kW WB Life you'd have ended up with better efficiency - they can modulate at a 7:1 ratio, giving a minimum output of 5kW which would have suited your system much better. You'd have also had slightly better hot water performance.

 

[Stotty1]

Have you the Worcester specific control kit installed, or are you using older, more basic on/off control? The proper kit will anticipate the need for the boiler to begin to back down its output, reduce gas consumption, reduce the heating / cooling ticking and maintain a more stable temperature.

We have a Worcester Comfort II RF control unit and Honeywell Home valves on each rad.

 

[Stotty1]

Thank you @muggles, @Harry Bloomfield and @ericmark for all your replies, it has been a big learning curve for me.

I'm very disappointed in myself for letting us get into this position to be honest.

The worse thing being we actually paid a little higher for the work as the company we used is highly recommended in the area.

But as ericmark said I now need to work out what to do to correct it rather than kicking my self with what should have been done.

 

[Harry Bloomfield]

We have a Worcester Comfort II RF control unit and Honeywell Home valves on each rad.

I don't think you can better that system.

 

[Stotty1]

Just a bit of feedback on my boiler using to much gas.
I have spoken with WB and they agreed the minimum output of the boiler was a bit high for my system.
As @muggles said the heating output is 24kw with a minimum of 7kw.
But apparently you can turn the output down on the boiler to say 15kw which will in turn bring down the the minimum output to something more suitable for my system.
They are going to ring and talk me through it later, so fingers crossed this will reduce my gas usage.