Unvented Tank Advice Please

[sharonbetty]

Hi. I have looked at similar posts but not seen exactly what I'm after ... unvented Gledhill 200l fitted a few months ago. A few weeks after and since most times when we turn on hot water tap in the morning there is a long groaning sound (I have a recording if it helps). Have contacted installer but they won't respond to me. Presumably I will have to pull up my big girl pants and pay for a new good installer to come fix - however since it only happens first thing in the mornings would I have to make a 6am appointment Seriously though any thoughts on what it could be and could it be damaging to the tank/pipes etc whilst it's left as it is? I may be be imagining it but I think it's taking longer for hot water to come through than it used to before the new tank ... thanks

 

[John.g]

There's been all sorts of explanations put forward for these noises ranging from improperly cured foam insulation to simply that the cylinder wall thickness is too thin.
Since it only happens in the morning? then the cylinder pressure will be a bit higher if heating overnight, say 3.8bar if PRV set to 3.0bar and could up to 5bar or so if the PRV is passing even slightly so you would have release ~ 3L of HW in the first instance and ~ 6L in the second instance to allow the pressure to fall to 3bar or lower, don't know if this has any bearing or not on the noise but it may if it only lasts for say 20secs or so, you could just let a tiny trickle of HW flow from a tap overnight to keep the pressure at 3bar or whatever and see if the problem persists in the morning.

 

[ShaunCorbs]

Expansion vessel not set correctly / too high

 

[John.g]

Why are pressure gauges not installed on these unvented cylinders which after all are pressure vessels?

 

[ShaunCorbs]

Why are pressure gauges not installed on these unvented cylinders which after all are pressure vessels?

Extra cost for manufacturers and tbh not needed

 

[sharonbetty]

Extra cost for manufacturers and tbh not needed

I suppose the question is .... is it damaging anything having this issue? If it is a pressure issue then surely there does need to be a "fix" ??

 

[sharonbetty]

Expansion vessel not set correctly / too high

Thanks for this. Presumably I need to ask a heating engineer to come and fix??

 

[sharonbetty]

There's been all sorts of explanations put forward for these noises ranging from improperly cured foam insulation to simply that the cylinder wall thickness is too thin.
Since it only happens in the morning? then the cylinder pressure will be a bit higher if heating overnight, say 3.8bar if PRV set to 3.0bar and could up to 5bar or so if the PRV is passing even slightly so you would have release ~ 3L of HW in the first instance and ~ 6L in the second instance to allow the pressure to fall to 3bar or lower, don't know if this has any bearing or not on the noise but it may if it only lasts for say 20secs or so, you could just let a tiny trickle of HW flow from a tap overnight to keep the pressure at 3bar or whatever and see if the problem persists in the morning.

Thanks for this - my husband says he'll cogitate!

 

[king of pipes]

It is really the responsibility of the installer to rectify this any reputable engineer should stand by his work for 12 months, first thing to check would be the expansion vessel is set 0.2 bar below 3 bar water pressure , the combination valve would be the next culprit checking water pressures before and after it and the nrv , if these are found to be ok I would be contacting Gledhill there has been issues with some cylinders in the past make sure you have the details of it's date of manufacturer and exact model - serial number ect it should be on a data sticker on the cylinder again you have warranty on the unit use it ? as long as it's fitted to the manufacturer's installation instructions and registered then any replacement of parts and a service call should be free , post a few pictures of the install please .
Regards Kop

 

[sharonbetty]

It is really the responsibility of the installer to rectify this any reputable engineer should stand by his work for 12 months, first thing to check would be the expansion vessel is set 0.2 bar below 3 bar water pressure , the combination valve would be the next culprit checking water pressures before and after it and the nrv , if these are found to be ok I would be contacting Gledhill there has been issues with some cylinders in the past make sure you have the details of it's date of manufacturer and exact model - serial number ect it should be on a data sticker on the cylinder again you have warranty on the unit use it ? as long as it's fitted to the manufacturer's installation instructions and registered then any replacement of parts and a service call should be free , post a few pictures of the install please .
Regards Kop

Thank you very much for this. I will get some photos taken