Radiators not fully hot

[wijcc]

My radiators are not fully heating up, they are not getting very hot and not hot towards the bottom on the radiators. I have bleed them all of air. My hot water is hot and working great, I have a Baxi Combi 80 Eco boiler, I have refurbished the diverter value on it. I will try switching off all the radiators barring one and see if it gets fully hot and hot through the whole radiator.
I flushed the system with Fernox F3 about 3 or 4 years ago and then put in Fernox F1 inhibitor in it. If I drain the system again, should I flush it with F3 again, or just drain and refill with fresh F1?
If it is a balancing issue, anyone have advice on best way to balance the system? Should the flow pipe be fully open on the radiators or open for one full turn of the valve? With regards to the lock shield valve do I open it by a certain amount of turn, a half or quarter turn for example?
I have noticed that when on heating the boiler does not stay ignited continuously it stop-starts. When running hot water the boiler flame stays ignited as long as the hot water is running. Is that normal?
Thanks in advance

 

[veedee]

Could be gunk/ sludge at the bottom of rad.

Every time I have had this issue using Sentinel X400 has done the trick.

 

[wijcc]

Is that better than using Fernox F3 cleaner and then F1 inhibitor?

 

[wijcc]

Very frustrating, I tried closing off all the radiators except one to see if it was balancing issue but that did not work as the radiator which was left on did not get hot at all... which prior to closing the valves on all the other radiators did get hold. I have tried opening the valves on all the radiators again but now none of them are getting hot. The pump is spinning fine and getting hot. The hot water works fine still with no issues. Does it point to a blockage in the pipes/radiator or could it be in the diverter valve, I did refurb it using a kit from ebay already.

 

[wijcc]

The heating flow pipe is hot under the boiler too.. but none of the radiators or the pips on either side of the radiators. The first pipe in the picture attached (1st pipe on the left is hot)

 

[terryplumb]

Sounds like there is no flow. Given that you have worked on the diverter ,did heating function at all after you worked on that ? If it did ,then the pump would be the next suspect.

 

[Notch7]

Sludge in the system can shorten life span of pumps and clog diverted and check valves.

 

[wijcc]

The pump seems to be working, it is spinning, making noise and getting hot.
It was working yes, just the radiators were not getting very hot and only hot towards the top only. I then switched off the valves of all but one radiator to see if was a balancing issue but that did not work, the single radiator did not hear up. I opened up all the valves on the radiators and none of them are heating up

 

[wijcc]

how can you diagnose if it is the diverter valve or not? Both the pushrods come out and activate the microswitch on it when the CH is activated.. can there still be blockage or parts in the Diverter valve not working properly, is worth me taking it apart again or getting another refurb kit for it and changing the internals on it again?

 

[terryplumb]

Bound to be the diverter valve ,isn't diverting !!
Are you certain the pump is good ? Take it off and Examine it.

 

[wijcc]

the pump spins fine.. is making all the right noises and getting hot. I undid the middle screw, water came out and used a screw driver and it was spinning/turning without any issues. What else do I need to check on the pump?

Also will just taking apart the diverter valve and reassembling it be sufficient given that it has had new parts inside two weeks ago approx or should I get another refurb kits? Both the push rods on the diverter valve pop up as they should when running.

Thanks for your help

 

[terryplumb]

You appear to have manually turned the pump ,but with boiler / heating turned on is it spinning ( electrically propelled )?

 

[wijcc]

I have undone the screw on the middle of the pump and when the boiler is activated HW or CH is switched on it is spinning. i can see it spinning and when touch it with the screwdriver feel is spinning.
It is the diverter valve, the refurb kit I got off ebay must not have been the best quality, I had to use a screwdriver to push the pushrods fully in and out on the diverter valve to get everything workings as it should do. Where is the best place to get a good quality diverter valve refurb kit from?

 

[terryplumb]

Baxi original part would be your best bet.

 

[wijcc]

Buying direct from Baxi?
I have previously used the refurb kits off eBay without problems.