no circulation

[billydkid]

can anyone help me?im having problems with my central heating.my boiler fires up and the temperture rises normally till it gets to 80degrees and ten knocks down.i thought it was a fault with my boiler.my rads dont get hot.its like there is no circulation around my heating pipes.can anyone give me some advice on how to fix the problem before we freeze our selves..ive a vokera condensing boiler.initially the fault was sayin that the flow temperture is too high,or differential between primary and return too high...would it be a fault with the pump circulating the heatin water..who ever replys cheers inadvance

 

[HERTS P&D]

Is the pump working?

Andy

 

[billydkid]

yeah the pump seems to be workin inside the boiler.

 

[misterdubya]

yeah the pump seems to be workin inside the boiler.

So, you can hear the pump - is that what you mean? Look up FAQ's on how to test a pump. The impellor may have detached from the shaft.

 

[BlueMoonMole]

Have you or anyone else 'topped up the pressure' recently?

I've had some numpty's this past few weeks who've isolated the Flow/Return whilst 'topping up the pressure' and it's led to no circulation.

Some basics to check:

If your heating is ON do any of the pipes beneath the boiler get hot?

After 10 minutes, and no less, do any of the other pipes get hot?

Now go to the nearest radiator to the boiler, or if you feel capable of identifying it, which radiator you believe to be the 'first on the circuit'

If any of the pipes below the boiler are hot, are they too hot to hold on to? is it hot for up to 1m? or more?

Try that lot, and then come back... Usually someone has turned off the taps under the boiler, and you'll merely have to turn them back on again.

 

[billydkid]

thanks for the msg boys.yeah the pipes are gettin hot under boiler.the pipes goin in 2 the rads are also hot but just no circulation around the rads.the boiler wont stay on for 10mins tho.wen the temp goes up the boilers knocks of.i did turn it on yesterday and the pressure released from the safety valve in boiler.anyway imgoing to drain down the heating system 2day and c does that help..the boiler seems to be workin and just shutting it self down before the heats dissipates around the heatin rads..anyway cheers for the replys.ill also look at the pumps faxs to see os it workin prpoerly

 

[PowerFlushAssociation]

If this happened over night; I would say pump, diverter valve, 2 or 3 port valves broken.
If it took a long time, getting slowly worse i'd say sludge build-up.
When you drain it if the water is really black, it's sludge.

 

[theheatinghelper]

is the 3 port / 2ports driving over ? if not try doing it manualy and see what happens !!

 

[billydkid]

i have 2 motorised valves in the hot press.one for hot water and one for heating the 6 rads in my apt.yesterday i drained down the heating to see was it sludged up.but the water was only dark and no sludge came out.i dont know how to check to c are the motorised valves working.but wen its calling for heat there comes on a light.wen its calling for hot water the other light comes on the myson motorsied valves.so i think there working...it must be the pump.ive tried to bleed the pump with a flat head and water comes out.and the impellers are spinning around.ive closed all the rads except the 2 nearest to boiler.there gettin warm.while the boiler is turning on and of.

 

[PowerFlushAssociation]

It is common to think that the water is only dark with no bits, so "you don't have heavy sludge" or a real problem. In reality the heavy sludge will not be moved by just draining it down, the flow is too weak for it's weight and you are only clearing some sludge on one path through the system NOT the whole system.
The black color is caused by the finest and lightest sludge, suspended in the water.

It depends greatly on where you drain from, so very roughly;
Brown water - some sludge / sludge still forming
Black water - loads of sludge

 

[billydkid]

last night i got all the rads warm by balancing the system.closin each rad and opening one at a time.would must sludge be in the pipework within a yr?as its a newly built apt.well if it is sludge in the water it is only brown..anyway ive a guy comin 2day so ill let u all kno wot the problem is..thanks 2all the people who replyed to me

 

[Dan Robinson]

In my experience brown is worse than black... often means a rad is about to go pop.

 

[billydkid]

well the guy came yesterday.and told me that the heat exchanger in my boiler is either blocked or damaged.the temperture in my boiler goes up so quickly and knocks itself off.