Radiators work, no hot water after turning off system.

[blakberry68]

This may have been answered in another post but my problem is a little more confusing (I have VERY little plumbing experience).

I turned off my central heating system (gas back bolier, gravity fed) and closed all valves in my upstairs airing cupboard then opened all my taps (kitchen and small bathroom) until water had drained. I fitted a new bathroom basin and then turned everything back on including opening all valves I had closed.

I have cold water and all radiators work fine however I no longer get hot water. I have an immersion heater which I can switch on in my airing cupboard and I get hot water, the water flow is not spluttering. I don't like using the immersion heater because it can get expensive so I am confused because I have obviously done something wrong. Any ideas?

 

[twgas]

when you turn hot water on do you get any noise from anywhere on system, ie pump humming, boiler clicking etc

 

[Softus]

You might not have opened all the valves. Can you post a picture of the pipework layout in your airing cupboard, including the valves?

You might have an airlock on the gravity circuit, but first check that the F&E cistern is full. This is a small cistern to be found either in your loft or at the top of the airing cupboard.

 

[blakberry68]

wow quick replies

I have opened all the valves fully and can hear no noise other than what I normally hear. I had a new pump fitted about 2 months ago plus the values above and below the pump. Everything was working fine until I turned off the system. There are three red valves and a tap next to the cistern. I turned all of these off and then on when I had finished.

I am at work now but will take a snap shot of my system this afternoon.
I could attempt to explain but my plumbing terminology is not the best. I could speak about IT and large computer systems though

Thanks for your help thus far.

 

[JohnD]

does "no hot water" mean "no water from hot taps" or does it mean "water from hot taps is not hot"?

is the cylinder higher than the highest radiator?

do you have a small tank in the loft which tops up the radiators and boiler? has it got any water in it?

if you bleed the highest radiator in the house, does water squirt out forcefully?

are the radiators hot? all over?

 

[blakberry68]

OK clarification:

Water is running out of the hot tap but is cold ie; water from hot taps is not hot.

Have bled all radiatators until no air is released and water trickles out.
All radiators are hot all over, no cool spots.

There is a cistern just above the boiler which is full of water. I believe there is another tank above that but I have not checked... which is an excellent point and I will have a look this afternoon. Thanks for that pointer JohnD will let you know the outcome.

 

[blakberry68]

also noticed Softus mentioned the tank in the loft, so thanks for that pointer also... hopefully its as simply as that

 

[D_Hailsham]

So you have heating but no hot water.

• How is the HW temperature controlled?
• Is it by a cylinder thermostat strapped to the side of the HW cylinder and a motorized valve?
• If so have you checked the thermostat temperature is set to 60C?
• Have you checked the motorized valve(s) are working.
• If you have only one motorized valve, is it locked in the manual position?

 

[Agile]

The pipe from the F&E tank may be blocked.

Tie up ball valve and note depth of water.

Bleed about 3 litres out of a rad and see if the level in F&E tank goes doem.

Tony

 

[blakberry68]

Checked the F&E tank there is about 5iches of water roughly half the tank full. If I press down on the ball valve water is let into the tank.

The thermostat valve strapped to the cylinder is at the 60C mark.

Not sure what the motorized valve is however there is a small metal box attached to a pipe to the rear of the cylinder (labeled Honeywell). I cannot tell you if that is functioning or not or if its set to manual.

I did notice the pump was set at level 1 so I switched that to 3 however its a brand new pump so I would expect that to be at 1 and anyway the only things I have touched is the main tap valve to the F&E tank plus the three red valves (gate valves?) ... I have stuck a pic in my album of my system. I will stick another pic of the F&E tank as well.

I might have to get a plumber in...

 

[holty]

looking at the pic. did you turn off the valve near the cylinder as it enters it .

 

[JohnD]

there is a considerable chance that you have insufficient water in the system to reach the top of the cylinder coil. This is most often caused by a blockage in the F&E pipe.

You have not responded on a couple of points which would help diagnose the cause:

is the cylinder higher than the highest radiator?

and

if you drain water out, is the same quantity drawn down from the F&E tank?

I asked
if you bleed the highest radiator in the house, does water squirt out forcefully?
and I understand you to say that it dribbles out weakly. this suggests that the cause is as mentioned.

 

[blakberry68]

couldn't get back to this post because of internet problems with my ISP.

If I bleed the highest radiator (its basically next to the airing cupboard) - the water trickles out. My next step was to extract a couple of litres of water out but by then another problem occurred after taking a shower because now I have no water coming out of my hot taps. Cold taps are ok but the water from the hot tap just flowed and then trickled then nothing. Just prior to this the shower pump went a little crazy and then everything went cold. Have checked in my airing cupboard and all pipes are cold except one which comes directly out of the top of the cylinder which is hot (I do have the immersion heater switched on). There is still about 5 inches of water in the F&E tank.

Would the above suggest an air lock or blockage as stated?

 

[Softus]

The following are the basic requirements for everything to work:

1. Water is being supplied to the cold storage cistern.
2. The float valve in the cold storage cistern is not stuck shut.
3. The cold storage cistern is not empty.
4. All valves between cold storage cistern and cylinder, and between cistern and pump, are open.
5. Water is being supplied to the F&E cistern.
6. The float valve in the F&E cistern is not stuck shut.
7. F&E cistern is not empty.
8. When you drain water from a radiator or drain off cock, water is able to leave the F&E cistern to replenish the system.

Until you check check all of the above it's pointless doing any more fault-finding.

 

[JohnD]

You have not responded on a couple of points which would help diagnose the cause:

is the cylinder higher than the highest radiator?

and

if you drain water out, is the same quantity drawn down from the F&E tank?