Hot water fine, but no heat to radiators?

[Santorium]

System is configured so that to get CH you must have HW on. All fine with HW, but no joy with radiators. They just went cold in the middle of the day.

Wall mounted thermostat makes expected click when twisted, so I'm assuming all fine there. Control unit lights up as expected and boiler def. fires up.

Have taken front of boiler and pump isn't doing anything which makes me wonder how I'm getting HW (tank is above height of boiler).

Any ideas where I start (except yellow pages under "heating")??

 

[Gas2Air]

You have a gravity fed HW system with pumped heating. Check the pump is running. Also if you have a motorised valve on the heating check thats opening up (valve should have a manual lever check if it's free to move), is there an anti-gravity valve fitted? Normally fitted after the pump.

 

[Santorium]

Thanks for the info. The pump (honeywell from memory) is definately not running is there an override switch to check whether it's broken or just not being told to run?

Question: How does the hot water from the boiler climb up to the hot tank?? Would have thought that gravity fed would have boiler higher than tank?

 

[Gas2Air]

I don't think the pump is honeywell. Basically your timeswitch or programmer sends power to your room stat, when demanding heat your roomstat turns on the pump. That's it. HW demand only brings the boiler on, as heat rises (did you do science?)through gravity your tank gets hot and gives you HW.

So you can elimanate boiler faults. Check for power at pump, or check for noise/vibration at pump, check impeller is rotating by unscrewing bleed screw or nut at pump. If all else fails give the pump a whack with a hammer....

 

[Santorium]

Will check on pump tonight and advise tomorrow, appreciate the help so far.

Yes, I read science which is why I still don't understand it being a gravity system. As the heat would rise, surely the only way for a hot water tank above the boiler to become heated is via convection, unless you're saying that cold water from the tank falls into boiler and rises again due to heat?

So I'm clear on this, you're saying that the room thermostat is what controls the pump? If so, I think we can conclude that it (thermostat)works okay (due to clicky noise when turning past ambient temperature), so that leaves me with power/impeller tests..

Will unscrew things and attack with hammer tonight and report back

 

[Santorium]

Gave pump a good smack with hammer, but zero joy Am assuming it's time to take it to pieces and look for gunge clogging it up?

It's definately not vibrating, but it was warm to the touch - should it be like this? Also it has a twisty dial on the bottom with numbers 1,2,3 - I'm guessing that these are flow rate and it should be set at the highest?

 

[ChrisR]

1,2,3 are pump sppeds. If you change it and hear/feel nothing, when the CH should be on, then your pump is not rotating. Undo the central screw like the nice man said. Insert a screwdriver to try to rotate the pump spindle, the end of which you have just uncovered. (if screw cap wont come right out you pull and turn IT.) A little water will dribble out.
If no luck check power to pump. If there isn't any then you have an cproblem, if there is you need a new pump.

 

[Santorium]

Thanks for the advice gents. One last question - do I need to disconnect the electricity supply before I go unscrewing the pump?

 

[kevplumb]

pump or screw in the middle

 

[mrcrow]

Yes, I read science which is why I still don't understand it being a gravity system. As the heat would rise, surely the only way for a hot water tank above the boiler to become heated is via convection, unless you're saying that cold water from the tank falls into boiler and rises again due to heat?

good luck with the pump...all hands on deck..
as for the gravity system..i thought this was just a generic term for convected water system...
you need energy to start it off...the boiler...then the hot rises and displaces the cold by convection...if it was gravity the cold would belt down the pipe..
gravity is what pushes the hot and cold 'gravity' supplies..(balanced) to your shower/sink etc...not including a mains sink cold supply..
i have a 'gravity' water and heating system...but the guys here are solving my problem as we speak..hot water tooooo hot..
cheers

 

[namsag]

Think this is a mickey take, studying science and doesn`t understand the absolute basic`s of a gravity system (heated water air etc becomes less dense and thus will rise and be replaced with cold denser stuff) and even suggests boiler should be above tank for this principal to work and then the question about disconnecting electrics before removing. If it isn`t and this is our future scientists god help us

 

[breezer]

regarding this

as heat rises (did you do science?)through gravity your tank gets hot and gives you HW.

obviously you "did science" but dind't listen that well,

it doesn't rise through gravity,gravity pulls things down, it is convection.

to quote my current fav tv prog "i can do science me"

click me to see some of the brainiac team (honest)

to see a couple of video clips click me

 

[Santorium]

Kev: screw in middle that opens to show pump spindle etc. Haven't taken one apart before, so don't know what to expect and just being careful.

Mrcrow and breezer: many thanks for the explanation on why it's called a gravity system that now makes sense.

Namsag: It's hardly my fault that I'm not familiar with erroneous plumbing terms is it? The heating in the system has nothing at all to do with gravity, only the water supply does, so get off your high horse. Incidentally as you've been kind enough to help me with my plumbing problem, I'll help you with your spelling, there is no apostrophe in 'basics'.

 

[brumylad]

Santorium, I think you've spelt your name wrong bud.

Their's bi too A's in sanatorium.

 

[Santorium]

Santorium be a an old nickname from school. No second 'a' required