No hot water!!!

[number49]

1 Switched the boiler off using the fused spur.
2 Drained the central heating system down by isolating the F&E tank and using drain cocks at the low points.
3 Left the heating off so I can add a new TRV tonight.
4 Switched the fused spur back on and reset the clock so we would have hot water this morning.

- Got up this morning and no hot water. Wasn't as cold as straight off the mains but was cold.

The time switch clock was the right time and the control panel showed the DHW as being ON.

It fired up for a few mins then the pilot light/flame went out and it was idle.

I tried switching it off at the fused spur again. Turned it back on and it fired again for a few mins then shut off.

Any ideas? Any obvious things I need to check? The heating has been off since July, but the DHW was working fine until this weekend.

I'm puzzled as I didn't touch the DHW controls etc, only drained the heating circuits. The only other thing I did was twist a gate valve which at first i thought was for isolating the F&E tank but figured out after it wasn't so I put it back to where I thought it was originally. But this was while the boiler was off.

It's as if the boiler thinks the DHW cylinder is up to temp and then switches off. Although it could be something completely different

The boiler is a Saunier Duval Xenon. There's a cylinder in the loft next to the heating F&E tank. I think the cylinder has it's own integral F&E tank sat directly on top, but this has a pipe which discharges into the heating F&E tank.


Mike

 

[bengasman]

Airlock

 

[kevplumb]

freakin boilers empty

 

[number49]

How do I fix it gents?

 

[kevplumb]

you could try filling the system with water

might be a long shot though

 

[number49]

Cheers!

How? The heating circuit is refilled, the mains, is on and the cylinder refills itself whenever the hot tap is used. How else do i get water into the sysetm?

The F&E tank is refilled too. What else? I know it might be a numb question but help us out it's fekin freezing...

 

[number49]

Do I need to bleed the heating circuit using the air valves on the rads?

 

[kevplumb]

The F&E tank is refilled too.

you didn't say that in your post

check the valve you altered might be the cold feed

 

[number49]

I thought that, but the valve is well open. I could see/hear it refilling as soon as I untied the ball valve too.

Any other suggestions?

Think I might need to bite the bullet and call a prof. Just bites as I've been careful not to **** about with things and only drained the heating circuits as described here: http://www.diyfixit.co.uk/central-heating/draining-down-a-system.html (I checked other places too to make sure I was doing it the right way)

I thought maybe switching it off at the fused spur without turning the boiler stat down to 'O' first may have tripped something I'd need to reset, but guess not. The programmer/timeclock was set to 'DHW off' at the time though so seems unlikely.

 

[number49]

Could it be an airlock in the heating circuit/boiler? Would bleeding all the rads again help?

 

[kevplumb]

View media item 667 View media item 11149 View media item 11148
if you have the valves they have a lever to lock them open to let the air out while filling

try bleeding the pump as pic

put an old towel or such under it first as there will be a spot of water dribbling

 

[number49]

Cheers kev. Fingers crossed I'll be back out of the dog-house by tea time

 

[bengasman]

Airlock

You could try backfilling.

 

[number49]

Managed to get it sorted.

Had the hot water working and all upstairs rads but downstairs were stone cold. The return from one of the downstairs rads was hot but the feed was cold... did a spot more draining and venting, vented the pump and switched the mid-port valve to manual (back to auto now) as mentioned by kevplumb and finally got it all going.

Rad's are all hot to touch and the mrs had a hot shower so I'm back in the good books...

Did consider backfilling, bought a hose on my way home just in case but didn't need to in the end. Other than venting the rads etc over the next few days and tweaking the lockshield valves to suit the new layout is there anything else I should do/check on?

 

[kevplumb]

is there anything else I should do/

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