Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 10 replies
  • Subscribers 32 subscribers
  • Views 808 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Potential Domestic Unvented Hot Water Cylinder Issue.

Zoomup
Mornin' All,


yesterday I visited a horse stable block in the middle of nowhere. One of the stalls has been converted into a "utility room" for caravaners. It contains a cheap dim L.E.D. ceiling light, a washing machine, a tumble drier and a small domestic unvented water heater for hot water, containing two 3kW heating elements, all run on a 4.0mm2 underground S.W.A. cable about 100 metres away in a house. But that is not the issue here.


The unvented cylinder has lots of copper pipework attached, all with no thermal insulation. Bearing in mind that this "room" is a very well ventilated horse stall outside, what are the main safety concerns regarding the unvented hot water system?


Thoughts please.


Z.

Parents
  • 0
    Steam explosions can indeed be very powerful. Any modern cylinder should have at leat three levels of protection though - on all electric ones it's usually the immersion thermostats, a non-auto resetting thermal cut-out and then a temperature/pressure relief valve. Freezing shouldn't really defeat any of those if it's installed correctly - since the problem will only arise when the water temp exceeds 100°C - at which point it's unlikely anything in contact with the cylinder will be frozen. There should be a tundish after the PRV so even if the outflow pipe has frozen water in it, pressure should still escape harmlessly.


    Freezing could well ruin the pipework and cylinder itself of course - but not an explosion risk I would have thought.


    It's all a bit different to the old back boilers behind open coal fires - which used to explode quite regularly when the feed/vent pipes to the cylinder or cistern in the loft froze.


       - Andy.
Reply
  • 0
    Steam explosions can indeed be very powerful. Any modern cylinder should have at leat three levels of protection though - on all electric ones it's usually the immersion thermostats, a non-auto resetting thermal cut-out and then a temperature/pressure relief valve. Freezing shouldn't really defeat any of those if it's installed correctly - since the problem will only arise when the water temp exceeds 100°C - at which point it's unlikely anything in contact with the cylinder will be frozen. There should be a tundish after the PRV so even if the outflow pipe has frozen water in it, pressure should still escape harmlessly.


    Freezing could well ruin the pipework and cylinder itself of course - but not an explosion risk I would have thought.


    It's all a bit different to the old back boilers behind open coal fires - which used to explode quite regularly when the feed/vent pipes to the cylinder or cistern in the loft froze.


       - Andy.
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines