Unvented Cylinder query

[Stevenworley]

Evening all.

First off, let me apologies for the laments terms that you may require to post any responses in!

i live in a block of flats, and have an ariston it 125 unvented cylinder heating system. The pressure gauge has historically always been on approx 1.5 bar for the previous four years.

I had some workmen in during my holiday, who turned off the system whilst performing their work. When i turned the system back on, the pressure went upto 3.5bar. Although this didnt really affect the flow of water in my flat (Think its restricted to 1 bar flow??) the airing cupboard was getting a bit toasty warm during the day. I dropped the pressure down to 2 bar a couple of weeks ago, and the system instantaneously starting dripping water out of this part:


It was a slow drip, about every 5 seconds or so.

When i came in last night, i cranked the pressure back down to one bar, and the drip started again. However upon my return from work today, it was more of a dribble than a drip and some was dripping over the side of the white (What i assume is a) waste pipe.Its now stopped, and hasnt been dripping for about 3 or so hours.

Am i right in thinking this is a release valve for the heater? dropping the pressure has created excess condensation, and it is dripping down a waste pipe?

Sorry if this is an absolute simpletons issue. I just need to decide whether i need to call somebody out, or whether i'm panicing at absolutely nothing.

Thanks in advance for any responses.

 

[diamondgas]

Is the water dripping hot or cold? Careful coz hot could be OOUCH!!!! 🙂

 

[Stevenworley]

i dont think its hot as there isnt any steam or condensation in the airing cupboard. its stopped at the moment, but can check if it starts again.

 

[Stevenworley]

Just scanning the forum, and it appears i have a tundish installed, and this is where the water is slowly dripping from.

 

[diamondgas]

You'll need someone registered to work on unvented cylinders Steven... Good chance there's an issue with take up of expansion! I'm not familiar with your particular cylinder ... Do you have a large white/blue spherical object in the same cupboard as the cylinder?

 

[Howsie]

Sounds like the builders put air too much water in but because you've used the safety device to reduce the pressure a bit of crud is probably caught I on the valve seat and it's no longer sealing.

 

[Howsie]

You could try turning it a couple of times and seeing if that clears it out.

 

[lbp plg & htg]

Warm water then its either the expansion vessel or t&p valve failed, cold water the expansion relief valve or Pressure Reducing Valve.

 

[Stevenworley]

hello mate. in the cupboard i have the main 125l tank, and then two smaller tanks high up in the cupboard (one is 8l, the other looks about five, one red one white)

the drip has just about stopped, but when it is dripping, its cold water. i have not lost access to hot water either.

apparently its a 'stored heat' system.

 

[diamondgas]

i dont think its hot as there isnt any steam or condensation in the airing cupboard. its stopped at the moment, but can check if it starts again.

If it stops when you run a hot tap then starts again a while later then the likelyhood is more towards expansion take up on the hot water side and unlikely to ber temp related! When your releasing pressure you may be relieving the pressure on the heating side, by-the-way not the domestic. Usually there isn't a pressure gauge on the domestic water side and it doesn't start to open till around 6/7Bar ..

The heating safety pipe is rarely attached to the tundish either 🙂

 

[lbp plg & htg]

Can you crack the nuts downside of t&p (90-95 10 bar)/ exp relief (6 bar ish) & expansion relief (3bar) and see which is wet? Red vessel heating side/ white potable water vessel. Tap the vessels - hollow then there ok but dull thud tells you the vessel diaphragm has perished.

 

[Stevenworley]

Can you crack the nuts downside of t&p (90-95 10 bar)/ exp relief (6 bar ish) & expansion relief (3bar) and see which is wet? Red vessel heating side/ white potable water vessel. Tap the vessels - hollow then there ok but dull thud tells you the vessel diaphragm has perished.

crack the nuts a what what? having tapped the red and white tanks, they are both sounding hollow.

having placed a piece of kitchen roll in the tundish, there is only a very slight damp patch on the cloth over a three hour period. i cant physically see a drip anymore if i watch it for a couple of minutes, and the water certainly isnt trickling out as it was before.

am i wrong in thinking that dropping the pressure bar in the heat tank would result in some water being displaced, through a waste pipe? it looks like a hepvo valve may be fitted underneath the tundish as well.

to surmise, its been 4 hours and there hasn't been any more considerable water drips since. is it just something i have caused by dropping the bar in the tank??