Strange Central Heating / Radiators issues

[scotthud]

Hi, ive noticed that 3 of the downstairs radiators dont get hot when the heating comes on, all the others in the house do (6 upstairs and 5 downstairs do) after reading on here and other forums/youtube ive tried to rebalance the radiators, all got hot, great i thought, then the hot water kicked in and the downstairs radiators got cold, i turned the hot water off and the downstairs radiators all heated up again?

Is it the pump Gundfos Alpha 2 ? sat at 32w, the valve seems ok as it switches between W M H ?

Thanks as alwyas

 

[terryplumb]

See if the hot water cylinders flow / return pipes (to the coil inside the cylinder) are fitted with a gate valve on either of them ,which is used to throttle down the flow into the cylinder.
How long have you lived at the property,and when did these radiators start to not heat ?

 

[scotthud]

lived here since it was built over 20 years, what do you mean by a gate valve?

 

[fixitflav]

lived here since it was built over 20 years, what do you mean by a gate valve?

But is it a recent problem?

 

[terryplumb]

lived here since it was built over 20 years, what do you mean by a gate valve?

It's a brass valve on a pipe ,they often have a large ,round ,red coloured wheel head handle. But not always.
As asked already ,when did the cold rads problem start ?

 

[Johntheo5]

Hi, ive noticed that 3 of the downstairs radiators dont get hot when the heating comes on, all the others in the house do (6 upstairs and 5 downstairs do) after reading on here and other forums/youtube ive tried to rebalance the radiators, all got hot, great i thought, then the hot water kicked in and the downstairs radiators got cold, i turned the hot water off and the downstairs radiators all heated up again?

Is it the pump Gundfos Alpha 2 ? sat at 32w, the valve seems ok as it switches between W M H ?

Thanks as alwyas

I remember your thread "Air Lock I think"

You have a 45W Alpha 2 (red) pump, it can quickly established what kind of flowrates its producing once its mode/setting is established, can you post a close up photo of the pump front, LEDs etc. while running., otherwise the 32W means nothing.
If its set to CCIII, its highest setting @6.2M, then its circulating ZERO at 32W.
If set to CCII, 3.3M, its circulating [email protected] @ 32W, then thats good.
If set to CP2, 4.5M, its circulating [email protected] @ 32W, not great.

 

[scotthud]

I remember your thread "Air Lock I think"

You have a 45W Alpha 2 (red) pump, it can quickly established what kind of flowrates its producing once its mode/setting is established, can you post a close up photo of the pump front, LEDs etc. while running., otherwise the 32W means nothing.
If its set to CCIII, its highest setting @6.2M, then its circulating ZERO at 32W.
If set to CCII, 3.3M, its circulating [email protected] @ 32W, then thats good.
If set to CP2, 4.5M, its circulating [email protected] @ 32W, not great.

Hi mate yes, i think its all linked to that original thread to be honest. So i would say its been going for over a year but only noticed it when i posted that thread Apr 24. Today the radiators upstairs were hot (valve was only open a fraction less than a qtr turn) downstairs were luke warm and the usual three were cold, as soon as i flicked the hot ware off the radiators have all got hot apart from one (this is the one that i took off and flushed in the original post back in Apr 24) ill get you some pictures of the pump.

 

[scotthud]

It's a brass valve on a pipe ,they often have a large ,round ,red coloured wheel head handle. But not always.
As asked already ,when did the cold rads problem start ?

Hi Terry over a year ago but really since Apr 24 see other message in this thread. IS this the valve you are on about, the pipes either side are cold? but hot wate is off at present?

 

[scotthud]

But is it a recent problem?

Not really i think its all linked to a post/thread since Apr 24

 

[terryplumb]

Very likely that valve ,but if it hasn't been touched ,and all radiators previously worked ok up until a year ago it's not likely to be that valve that's your issue.

 

[Johntheo5]

Hi mate yes, i think its all linked to that original thread to be honest. So i would say its been going for over a year but only noticed it when i posted that thread Apr 24. Today the radiators upstairs were hot (valve was only open a fraction less than a qtr turn) downstairs were luke warm and the usual three were cold, as soon as i flicked the hot ware off the radiators have all got hot apart from one (this is the one that i took off and flushed in the original post back in Apr 24) ill get you some pictures of the pump.

That pump according to the pump curves is circulating almost zero LPM, you say the rads upstairs were all hot with "valve was only open a fraction less than a qtr turn", what valve is this?, is it a valve on each rad?.
Are those pump power readings taken with just rads on?, if so can you change over to HW only and just note speed III power. When finished, change to CP2, LED on the extreme right and note the pump power.
I've a feeling that pump is faulty or the impeller & maybe the pump ports are full of sludge, I would switch off the boiler, shut the isol valves on either side of the pump, remove the four stud bolts from the pump and lever it up & out carefully, inspect for sludge build up in the pump ports, get a tie wrap and push it through each impeller vane to prove clear.

 

[scotthud]

That pump according to the pump curves is circulating almost zero LPM, you say the rads upstairs were all hot with "valve was only open a fraction less than a qtr turn", what valve is this?, is it a valve on each rad?.
Are those pump power readings taken with just rads on?, if so can you change over to HW only and just note speed III power. When finished, change to CP2, LED on the extreme right and note the pump power.
I've a feeling that pump is faulty or the impeller & maybe the pump ports are full of sludge, I would switch off the boiler, shut the isol valves on either side of the pump, remove the four stud bolts from the pump and lever it up & out carefully, inspect for sludge build up in the pump ports, get a tie wrap and push it through each impeller vane to prove clear.

sorry yes it was with the RADS only on and sorry yes i meant the rad valves i left them hardly open to try and push the flow to the downstairs rads especially the three problematic ones (valve fully opened on these 3) the other downstairs ones are again just cranked open a qtr turn. Right ill go switch it over to HW only and take some more photos, this is with just the water on and i ve added the divertor unit to show thats working as it moves to W to H

 

[Johntheo5]

OK, again pumping zilch according to the pump curves, one last test, leave it on CP2 and get a adjustable spanner and shut the pump Discharge (outlet) valve only for say 5 secs, note the power, reopen the isol valve, if the pump is pumping upwards the discharge valve is the top valve, also just ensure that the arrow on the pump body is pointing in the direction of flow, ie, towards the diverter valve.

 

[scotthud]

OK, again pumping zilch according to the pump curves, one last test, leave it on CP2 and get a adjustable spanner and shut the pump Discharge (outlet) valve only for say 5 secs, note the power, reopen the isol valve, if the pump is pumping upwards the discharge valve is the top valve, also just ensure that the arrow on the pump body is pointing in the direction of flow, ie, towards the diverter valve.

Should i do this with it set to heating or hot water?

 

[Johntheo5]

Hot water.