NO HOT WATER. AARGH!!

scott6471 · 3 Sep 2007

Hi,
I have a Servowarm back boiler that was already fitted when we moved in. The system is Gravity fed; no valves of any sort and the hot water is not pumped.
When i moved a rad recently i drained the system and refilled when complete. For some reason i now have no hot water!!
I tried bleeding the system a number of times but the lower pipe on the back of the cylinder is cold (I guess this is the return flow). The top one is hot.
Am i getting an airlock in the coil? If so how do i clear it? Any thoughts would be greatly appreciated as the kids bath is being filled by the shower at the mo!!

Thanks

Rob · 3 Sep 2007

I only know one way that i cant recommend

Maybe try draining and refilling the system?

scott6471 · 3 Sep 2007

Hi Rob,
Thanks for the reply.

I'd already tried the re-drain method just in case i'd filled it up incorrectly. My research suggested airing the downstairs first as it fills up then the upstairs.

No joy!

If you whisper the recommendation i won't tell anyone

The Baker · 4 Sep 2007

Does the system have a header tank for the heating system?

If the answers no then due to the design of the cylinder, you may need to drain the system and the cylinder before refilling, also don,t add any inhibitor.

Tim

gas4you · 4 Sep 2007

Are you sure the system has filled up fully each time?

You could try banging the gravity pipes carefully, otherwise it would mean calling in somebody to do what rob is thinking of.

scott6471 · 4 Sep 2007

Hi,
Yes the system does have a header tank in the loft.

I've definately filled up completely as there is no air from any of the bleed valves, the pump or anything.

Am i right in thinking that Rob may be suggesting connecting a hose to the drain valve and then to a mains supply to force any air out? If so i'll have a go at this myself, hell i'll only have myself to blame if anything goes wrong.

Cheers guys

gas4you · 4 Sep 2007

Not what I was thinking that rob was thinking

if you follow that, but you could try it

namsag · 4 Sep 2007

What they are not telling you is try and boil system up by taking the thermostat phial out of its pocket , BUT only let it boil for a short period . It will sound like someone battering the sh#te into it with a hammer. This will usually move the airlock... Are you sure it is a servowam bb as i have never seen one in 30 years

gas4you · 4 Sep 2007

Brave man namsag, I wouldn't want a diyer to do this

namsag · 4 Sep 2007

Upto him but it is a diy forum not a trade forum dave

gas4you · 4 Sep 2007

Point taken, just didn't want him to crack his boiler open

gasandoilman · 4 Sep 2007

you said u get no air from rads...
But do you get water coming out???

Is the system filling

scott6471 · 4 Sep 2007

Hi Guys,
Thanks for the responses so far.

Apologies it is a Glow Worm BB not a Servowarm as suggested.

Yes there is water coming out of the rads when i bleed them.

As for removing the thermostat phile, i wouldn't even know where to find it let alone remove it!!. What are the possible downsides if i were to try this method?
Should i try forcing the air out first or is this method unlikely to work? From what i can understand connecting the hose should force all the air in the system out and apparently you can tell when it's done when the overflow from the header tank starts flowing; is this correct?

Thanks Scott

gas4you · 5 Sep 2007

All this will prove is that the hearder tank is full, not that you have got rid of the airlocks!

JohnD · 5 Sep 2007

Have you tried filling it from the bottom? F&E tank empty, hosepipe on the lowest drain-off spigot?

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NO HOT WATER. AARGH!!

namsag

namsag

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