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AnonymousBosch

Somehow I sense the warmth has gone out of our relationship

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We have an open vented central heating system with gravity fed hot water.

 

For reasons over which we will draw a polite veil, we (well 'I') drained the radiators, refilled them, flushed out what I  could: and ............made the heating problem worse. At the very best time of year for that to happen.

 

So, in a fit of rage and frustration, I re-drained the complete system took all the radiators off and, at long last, discovered what the problem is.

I don't know what I'm doing. 

 

Anyway, here's the thing: 's gonna get cold in the next few days and I'd like to stay married.

 

The 'boiler' is a multi-fuel fire. It has a back boiler which is now empty.

Please tell me I can light the fire anyway, even though there's no water in the heating pipes. In other words use the fire as a simple space and running hot water heater......

 

If I can't there's a nice warm hotel right next to where SWMBO works, and .... well you can guess the rest.

 

  • Haha 2

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When you say multi fuel fire / boiler, what exactly do you have? 4 pipes out of it, 2 to the DHW cylinder rising on convection / gravity and another 2 to the heating circuit via a pump  ?

Some pics would help maybe. ?

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Ok ...

 

do all the rads have bleed screws 

that work ..?

 

does the boiler have a bleed screw on the top of it ..?

 

If so, then close the valves to all the rads and open the fill valve for the header tank and let the boiler and system fill up. Bleed the back boiler if you can at this point so you know that’s full. 

 

Then one at a time, open a radiator valve and then open the bleed screw to let the air out. Work from closest to the boiler and ground up so lowest to highest. 

 

When you have done them all, turn the pump up to max and turn the room stat up and let the system circulate and go round again and drain the air out. 

 

Finally... light the fire and it should start to heat everything 

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17 minutes ago, PeterW said:

Bleed the back boiler if you can at this point so you know that’s full. 

 

It's gravity hot so the highest tapping should vent the boiler ;) 

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30 minutes ago, Nickfromwales said:

It's gravity hot so the highest tapping should vent the boiler ;) 

 

Should..... but some of the Baxi’s used to have a bleed screw as the top tapping was just below the top edge ...

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13 minutes ago, Nickfromwales said:

[...]

Did you hear fizzing and kettling from the boiler ?

 

 

Yes: and then it bubbles up into the top-tank (for the hot water)

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Then it's circulation issues. The water isn't flowing through the boiler fast enough so it's boiling ( kettling ). 

Have you got / did you try a new pump yet?

Can you cut the pipes on the boiler and connect the hose to them ? Sounds like a blocked or partially blocked heat exchanger. A power flush may sort it TBH. 

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Right. Thanks @Nickfromwales

 

Now the key  question: the one that'll make the  coming week bearable or Hell. It's up to you, Nick.

 

Can I light the fire  to provide a bit of radiant heat? 

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8 minutes ago, recoveringacademic said:

Can I light the fire  to provide a bit of radiant heat? 

I still don't know what appliance were dealing with :/. Does it have a dedicated burner for the boiler, and a separate fire 'front' ? Eg could you light the forefront without getting hot water and heating ?

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  Another typical problem is that any the thermostatic values are sticking.   Also have you got a sludge filter in your system.  If so when did you last clean it out?

 

17 minutes ago, Nickfromwales said:

Sounds like a blocked or partially blocked heat exchanger

 

if the back boiler is new enough to have one.  Do you know the make, model and approximate age of the fire and backboiler?

 

Do you know what your topology is?  If you have multiple loops in parallel, then you might have balance or backflow issues, especially if you have non return valves missing in some of the loops.   Another potential issues is airlocks in any swan-necks on feeds etc., or in the boiler itself.  If you have multiple loops then an airlock in the boiler path might just result in the pump circulating the water down one loop and backwards down another without circulating through the boiler at all.  A diagram might help.

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Yup this system might be 30 years old and never routinely maintained or it might be a modern design.  Different probable failure modes.

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Can't he flush this using mains water?

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16 minutes ago, TerryE said:

if the back boiler is new enough to have one.

Errr....a 40 year old baxi 551 has one ;)

4 pipes means this has deffo got a PRIMARY heat exchanger, much as just about any heat only boiler would have. 

Agree it could be circulatory issues and air locking too but the DHW should circulate without kettling even with no heating connected. 

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5 minutes ago, Onoff said:

Can't he flush this using mains water?

That's why I asked about cutting into the 4 pipes ;). Connecting cold mains to the lowest tapping should result in water coming out of the other 3. 

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