Hello,

I'm a reasonably competent DIY plumber, so the question is whether I need to call in outside help to clear a blockage I have in my downstairs hot water supply? Do I need special equipment, and if yes can it be hired?

Background: my local (UK) council did some work on the cold water mains which in turn caused an issue for me with my cold water pressure. While they were solving that problem the hot water flow to downstairs dropped in half - I don't know exactly how this was caused, but our theory is that the stop cock to the main hot water feed to downstairs (hot water tank on first floor) was opened and closed and the washer had perished. After replacing the valve the flow is still poor, but if you by-pass the pipework under the floor by connecting a flexible hose to the bottom of the valve and the kitchen faucet the flow is fine.

So I have a blockage in my pipe under the floor somewhere between the valve and the tap. To complicate matters I have two sinks and a shower downstairs - all of which have poor water flow, so the pipework branches under the floor as well. Logic suggests the blockage is where the branch occurs as it is likely the diameter of pipe chanegs at that point form 22mm from upstairs to 15mm.

The council helpfully tried using compressed C02 to try and clear the pipe for me but that had no positive effect.

Are there any other things I can try myself ave ripping the floor up (tile covered) and cutting into the pipework??

Any suggestions gratefully received!

Thanks

Steve

colbtech

Maybe its a simple air blockage (downstairs I know it shouldn't happen but...) try connecting your mains cold water (this is under pressure to the pipework going to the downstairs units. and turn on the taps...see what happens shoudl; clear the blockage. The trick will be to connect everything back up and avoid the same result.

I presume that the upstairs hot water is ok?

rattyvulcan

Thanks for the reply.

The council plumber tried that so didn't think it was an air lock.

Upstairs hot water is fine....

colbtech

OK, I presume when they connected the cold supply the water came out ok? What about connecting the hot feed to the hose and seeing what flow you get then? I presume that there is a T-off to downstairs it is possible that the blockage is before the valve?

rattyvulcan

I couldn't have been clear in my original post as the hot was connected a hose below the valve (and the hose then to the kitchen tap) and the flow is fine, so the blockage must be after the valve.

Interestingly the cold supply pressure is still not back to the level it was prior to the work being carried out by the council, but I've had the waterboard around and they've measured the flow etc and claim they are delivering within the parameters that they are contracted to.

colbtech

apologies for my inability to read and remember what was written. I put it down to age, stupidity or too much beer at the weekend.

is the hose the same or similar diameter to the pipework downstairs?

sorry but i reckon that during the council works a stone or something larger than 15 mm but smaller than 22 mm has got in your pipes. Hopefully you know where the 22 mm changes to 15 mm and open up the pipes...Good Luck!

rattyvulcan

You've come to the same conclusion as myself. Unfortunately, the only thing I definitely know about the position of the 22mm to 15mm reducer is that it is under my tiled floor. :/

Thanks for your input.

colbtech

let us know how you get on. You should be able to get some sort of compensation from the council. After all it was their workmen that mucked up your waterworks

mike the plumber

hello just a quick question! was the hose connected after or before the valve? as if its connected under the 22mm gatevalve then this would indicate if there is a blockage in the pipe work, if however the hose is connected above the valve then it would only show that the valve is still not repaired!. If you want to check for a blockage i would suggest that you connect a 22mm bend to the underneath of the valve and reduce it to 15mm(or if possible lead the 22mm pipe to a bath)and attach to a hose.once you have done this safely(make sure you drain the big tank/50gallon tank, by attaching a bit of string to the ballcock and tying it so the ballcock does not let any water through).once you have done this try to attach you cold kitchen tap to your hot kitchen tap(if you cant do because you have a mixer then put your hand under the tap and open the hot with the other hand, and slightly open the cold.WARNING you may get sprayed with water)This should force any blockages around the opposite way.good luck

rattyvulcan

The hose was connected after the valve, so I've proven that this is OK.

If I follow you correctly, you're suggesting to use the water pressure of the cold to 'flush' out the hot water pipe? I do have a mixer tap, but I have isolation valves for both hot and cold feeds to this tap so I could make the 'join' there. I could then use the main valve for the cold water in to control the pressure of the water into the pipe.

I may have to wait until the weekend before I can try this out, but I'll let you know how I get on.