Donate SIGN UP

Hot Water Not Flowing

Avatar Image
annieigma | 08:14 Sat 04th Aug 2018 | Home & Garden
12 Answers
Hi All,
Bit of a problem with hot water. situation is that when you turn the tap on ( any hot water tap in the house) the water flows nicely for about 10 seconds max, then it " bloops and gulps" after which the flow is very very poor, and does not improve after any length of time.
The header tanks have been checked to see that there is water in them, and the ball cocks operate good. the installation is only a couple of years old, its the old fashioned immersion tank system, the tank and everything is as new, never got used much as it is a rented farmhouse with just one occupant. We have searched for valves that may not be open properly etc.
Any ideas please?
Gravatar

Answers

1 to 12 of 12rss feed

Best Answer

No best answer has yet been selected by annieigma. Once a best answer has been selected, it will be shown here.

For more on marking an answer as the "Best Answer", please visit our FAQ.
Could the vent from your hot water tank be blocked.
It feels to me that there is a partial blockage somewhere - perhaps a layer of silt at the bottom of the header tank. Water can seep very slowly past it; enough to give you a few seconds flow when you turn on the tap. Leaving the system for a long time allows the water in the header tank to seep past the blockage and fill the pipe up again.
1. Check the bottom of the header tank for silt.
2. If that doesn't work, wait until water stops flowing and then blow hard up the tap (tap still open, of course) - that should result in bubbles at the header tank and may clear the blockage.
3. If that doesn't work hope that "The Builder" sees this thread and comes up with a better solution.
Hot water would never normally come from the bottom of a tank, more likely from a hot water cylinder with a vent to the cold water tank, this needs to be unobstructed to stop any "vacuum" effect when drawing hoy water.
Sounds like an air lock. Do you have a mixer tap in either the kitchen or bathroom? If so turn on the hot. Now for the clever bit. Put on a marigold or rubber gardening glove and tightly press this hand on the bottom of the mixer tap. Now turn on the cold. This should force cold water up the hot supply pipe work and hopefully clear the airlock, which can be very hard top locate.
Donny - the vent pipe is there to allow expansion when the water expands due to heating, not to let air into the system. Air gets in via the header tank.
I had, though, overlooked to fact that the hot water feed is via the cylinder, so blowing up the tap will just cause bubbles to go up the expansion (vent) pipe.
Hopefully Togo's suggestion will work. We've had to have our HW system drained a couple of times to deal with a problem and each time we've had an airlock.

We've got power showers and our solution is to take of the shower rose, drop the house to the bottom of the tray and switch on the power shower for a couple of seconds. This usually clears the airlock, at least in our case. Do let us know if/how you get it sorted.
I think Togo's is the best sugestion so far, with the caveat that, if water flows from the vent pipe, temporarily block it to force the water to back-flow into the bottom of the header tank. This is a two-person job, as you need to be watching the header tank whilst running the cold-water tap.
Further to my first suggestion. If you have separate hot and cold taps a short length of hose from the cold to the open hot tap will also work. It may require someone else to do the turning on of the cold tap if you cannot fix the hose tightly and need to hold it in position.
I'd also say it is just an airlock.

Nothing for you to do regarding the system. All you can do is to try to clear it. Togo's methods are tried and tested. It's a bit of a game though. Assuming the kitchen has a mixer tap, I usually open the hot tap, place a large Builder's gob over the spout.......... and blow. There shouldn't be any need to monitor "progress". Keep blowing, and eventually, hot water should start to stream from the hot tap.

It's a bit hit and miss, I'm afraid, but you should get there eventually. A farmhouse (it's often old farmhouses) that's been "renovated", but incorporating an old-type gravity system, can throw up all kinds of problems. It's often down to poor pipework layout. Critical with gravity systems.

The main way that air can get in, is if the roof cistern (tank) runs dry. That is, running a lot of hot water (maybe a bath), when the supply to re-fill the roof tank is unable to keep up. Possibly from an undersized tank, or low mains pressure. Just a possibility.

Re-jigging the pipework layout properly will usually sort this out, but that's beyond your control I'm afraid.

An alternative method I often use .. tell the customer to boil the kettle and then place a teabag in a cup. At this point they usually underdstand the rest of the procedure.
No point in getting all red faced and almost bursting a blood vessel blowing up the pipe or spraying water all over the kitchen while trying to divert the cold water up the hot tap.
Having done both of these tricks in the past, I have devised a more genteel method, this will allow you to drink tea and watch the magic.

Get yourself a length of innertube from a bicycle tyre.
Cut it anywhere you like .. Now tie a knot in it, really tight. Cut the tube again so you are left with something like a condom with a knot at the end ...
When you have stopped laughing.. place the open end of the tube over the tap spout (if it's a mixer) and force it on until it is tight. It is then a simple matter of holding the tube on the tap, opening the hot tap fully and then opening the cold tap and allowing the cold mains pressure to force the air lock back into the hot tank.
... You can sip tea whilst doing this..

If you happen to have two single taps then do the same procedure using the length of inner tube you have left from the original experiment.. only dont tie the knot in it !

The reason for the inner tube is the walls of the tube are strong and will withstand the pressure of cold mains and wont expand and burst .. like a condom will.

My inspiration for this was born out of survival whilst working in front of customers and not wanting to look a fool as I soaked the kitchen window while moving an airlock.
I agree - hot to cold and both on to blow out airlock.

An alternative, which can be quite wet and messy and depends on how the exit from the header tank is located, is to use an old fashioned sink plunger inside the (at least half full) header tank over the exit, giving it lots of welly (with a hot tap open somewhere in the system of course).

Good luck.

1 to 12 of 12rss feed

Do you know the answer?

Hot Water Not Flowing

Answer Question >>