Noisy water in central heating system

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Staffordshire
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Hello, I have recently had a new CH system installed which consists of Gloworm 24kW A rated condensing heat-only boiler, CP53 3-speed circulating pump and a new thermal-store type hot water cylinder. The system works well however the only drawback is that on startup there is a rather loud "kettle coming to boil" noise localised around the pump area. However this noise only lasts for about 2-3 minutes and after that it goes away and the pump silently circulates the hot water through the radiators etc etc. It almost sounds as if on system startup water is coming to boil and then after a few minutes the boiling noise goes away as the system settles down. The pump is set on speed 2, the boiler is set to 80 degreec C, the radiators have been bled and I believe they are free of any air and the system has been recently flushed and treated with sentinel corrision inhibitor.

Any advice as to what can be done to minimise this boiliong noise would be greatly appreciated. Thank you.
 
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how recently was it installed?

How reputable was the installer?
 
The system was installed in February this year so that makes it approx 4 months old. The installer/plumber is a decent bloke and he certainly has track record on doing this sort of installation (I know this may not mean much but I did visit some of the commercial and domestic installations which he did in the past and they seemed fine).

As part of the CH replacement process very little pipework was replaced; basically the new boiler was placed in the same location where the previous boiler used to be, the new circulating pump was placed in the same spot where the old pump used to be etc etc. what hasnt changed is the expansion tank in the loft (i have an open vent system). The previous CH system was a Worcester 15kw boiler with a Grundfos pump and that system was certainly a lot quieter than this one.
 
4 months old? :eek:
Don't touch it, get the installer back to rectify the problem.
If you touch it, he can blame any problems on you and refuse to do any warrantee calls on it.
And he would be right.
 
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Hi there, I have not touched anything, I wouldn't know where to start. He has been in already three times, got a new pump which made no differece, put the old pump back in, drained the system twice but the problem doesn't seem to go away. It also seem that the plumber who installed is also running out of ideas; the only thing that he didnt do is try out a new boiler but i doubt that is going to help. I was thinking i could get another plumber in to have a look at it and perhaps she may be able to shed some light on it.
 
unusual sounding fault, out of interest what boiler model is it? also why is it on 80? thats excessive, especially this time of year.
 
Hi there, the exact boiler is Glow Worm Ultracom 24hxi open vent boiler. The reason it is on 80 degrees is because the plumber who installed said that the boiler should alway be on the max temperature setting for maximum efficiency. The inside temperature is governed by the Climapro sensor and that turns the boiler on and/or off as needed to maintain the desired indoor temperature. The plumber said that in order to maintain the best efficiency the max temperautre should be set on the boiler and i could only take his word for it.
I wouldn't say this "fault" that i am experiencing is a fault as such, more of an annoyance; it is certainly the first time I noticed this sort of "boiling water noise" localised to the CH pump. could it be that there may be some air trapped in the pump which needs bleeding?
 
Hi there, the exact boiler is Glow Worm Ultracom 24hxi open vent boiler. The reason it is on 80 degrees is because the plumber who installed said that the boiler should alway be on the max temperature setting for maximum efficiency.
A real star.
The lower the temperature a condensing boiler works at, the more efficient it is.
Apart from where the cylinder stat is set higher than the boiler stat, which causes perpetual cycling, it is never more efficient to raise the boiler stat.
 
Hello bengasman, thanks for the advice. So are you thinking that because the water from the boiler is at 80 degrees , this is very close to boiling temperature and this could be the cause of the unusual boiling sound? For you information, the indoor temperature controller is set at 21 degrees.

On the thermal-store HW cyclinder I have a thermostat (located towards the bottom end of the cyclinder) which is set at 70 degrees and another temperature sensor (located towards the top end of the cyclinder) which reads approx 5 degrees less than what the thermostat is set at (in my case 65 degrees). Again, these are the default settings that were set by the plumber. Is my hot water setting too high?
 
Are you in a hard water area?

have you had to top up the water since it was installed?

You say it is open-vented, so I presume it was fitted to an existing old system. How was the old system cleaned before the boiler was changed? What Inhibitor was added? Have a look at the Feed & Expansion tank in the loft and describe to us how clean it is, and if it has mud at the bottom or scale up the sides
 
Your noise could be caused by a number of things, and is probably a combination of several.
It sounds like a poor install and could probably do with a complete system check over.
Personally, I loathe open vent systems and consider them something left from the previous century; they have several disadvantages, and no positives.
 
Hi there, sorry for the delayed response. I live in a relatively clean water area (stoke on trent) and I say this looking my kettle element which is virtually scale-free. I did go up in the loft and had a look in the expansion tank and the water was clean; there was very little limescale on the side of the tank and overall everything looked in good nick.

I did some research and experiments this weekend with the various controls in the system and what I have noticed is explained below. I have my thermal-store hot water cylinder normally set at 62 degrees; as hot water is being used to prolonged periods of time, the temperature inside the cylinder drops. As you'd expect the boiler kicks in and starts re-heating the water inside the hw cyclinder and I suspect that the difference between the flow and return gets bigger than 20 degrees C. This causes the boiler to work at its max temperature (80 degrees C) until there is a difference of less than 20 degress C between flow and return. It is only during this time that the "boiling water" noise can be heard as the pump circulates the hot water through the hw cyclinder; once the hw cyclinder reaches a temperature that is withint 10 degrees of what it shoudl be. the "boiliong water" noise from the pump stops and the pump becomes smooth very hardly any noise at all. Let me give you an example....every morning me and the lady have a shower pretty much at the same time, me in the en-suite and she in the main bathroom. Both our showers are Mira mixer showers with the hot water feed coming from the thermal-store cylinder. When we finish the showers, I make a point of checking the temperature on the HW cyclinder and it is ususally down to 48-50 degrees C (from 62C) and my circulating pump is pumping away hot water and the annoying boiling water noise can be heard from the bedroom. We then have some b;fast, coffee, morning news etc etc a procession which usually lasts for about 30-40 minutes and again once this is over and done with, i go back upstairs to have a look at the temperature on the HW cyclinder...usually by this time it gets to about 58-60 degrees and the pump is still working away but this time no more "boiling water" noise. So there you have it in simple terms. What i have just said could be a lot of non-sense but this is what i make of it so far.

Bengasman, the reason I went for an open vent system was because the plumber said that because the previous system was also open-vent, if we go to a sealed system the radiators pipes might leak because there were never designed to take that sort of pressure. I know hindsight is a wonderful thing, but I have to live with what I got. Can you give me just a few exmpales of what could b wrong? I do agree with your suggestion of somebody competent having a good look at it and give it a thorough inspection...this is what I intend to do.

Thanks.
 
So you've got a thermal store? what model is it? if this is case then yes you may have to have the boiler on maximum.
fya the boiler will modulate down to achieve a lower difference between flow and return not up. If the difference is regularly going over 20c then the circulation is not what it should be and could be an indication of your problem. You can check the flow and return temp quite easily with D codes 40 and 41. access to D codes will be explained in the manual.
 
It seems we have established the installer was not overly competent, so I suggest you ignore whatever "advice" he gave you.

Start by limiting your boiler stat to 70 in stead of 80.

The higher the temperature, the more limescale deposits you get.
Search the forum for limescale removers for your particular type of boiler, or contact Fernox or the boiler manufacturer.
One advantage of an open vent system is that it is very easy to add chemicals.
Follow the instructions for use of the chemical and see what happens.
I expect that these 2 measures will be enough to solve the problem.
 
Mickyg - the thermal store cylinder is a gledhill torrent t200 indierct with solar upgrade capabilities. I have simulated the cyclinder "cooling down" by running a hot bath and the cyclinder temperature went down to about 46-48 degrees and as before, this triggered the annoying "boiliong water" noise at the pump whilst the cyclinder was being heated up again. While this was going on I went down to the boiler to check the the temperature on the boiler and it was constantly at 80 degrees with the boiler appearing to be working at full blast. Note that no radiators were working as the house is warm enough.

Bengasman - I will try setting the temperature to 70 C and also add the limescale remover. i take it the lime scale remover goes straight into the feed tank in the loft, right? No other opreation need?
 

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