Radiators not heating up.

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My Baxi Combi Boiler is only heating my radiators up to tepid.

The boiler is firing up okay, it is, according to the display heating the water to temperature and then the boiler is stopping gas. The radiator light on the boiler is coming on. One or two radiators on , I think, the front end of the circuit are getting hot the others not. The hot water is working just fine.

My thoughts were that the pump was problematic. The pump sounds like it is running and the send pipe to the heating is getting hot by the boiler. The pump itself is getting hot. The return pipe is tepid.

I tried tapping the pump with a hammer. I loosened the screw to check for air. I i turned the system off, isolated the boiler from the system and removed the from screw from the pump to check for debris, (very small amounts of dust), and to check that the pump turned freely, (it did).

All of this to no avail.

Given that the boiler is going on and off more or less as it should, I am still thinking that the pump is the problem, but before I shell out £130 for a new one, I just thought I'd check with you who know this stuff better than me.

Any thoughts guys?

Thanks
 
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With the pump running undo the screw on the front and try stop the impeller.
If you can stop it then the pump is weak and new one requird
 
Turn all the rads off except the nearest one to the boiler, and then add the, back into the system, and see what happens. If the rads heat up evenly, then it'd be the pump, but if there are cold spots at the bottom, then that suggests a dirty system.

If the return pipe is tepid, then either the pump is failing, or there's crud in the pipes as well as the rads.
 
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With the pump running undo the screw on the front and try stop the impeller.
If you can stop it then the pump is weak and new one requird

I can't ... but I could only touch the hub of the impeller. I tried with the end of a screwdriver, (it was pretty hot).
 
When was the last time the central heating system was cleaned?

The system was professionally pressure cleaned last April. It was fairly clean then, (as in not much grime came out and the cleaning guy suggested that it hadn't really needed doing). Since that time there has been a magnaclean filter on the return pipe which has been checked every couple of months and produces very little.

I am fairly confident the system is pretty clean.
 
Before condemning the pump id be cleaning out the filter first! Grundfoss pumps are normally reliable.
 
Did they use x800 to clean the system?
If any amount of this stuff is left in a system then it is known to kill pumps
 
Did they use x800 to clean the system?
If any amount of this stuff is left in a system then it is known to kill pumps

I used F3 as a "pre soak" before he came. The pressure clean contractor used their own brand cleaner. The system got properly flushed afterwards and the water tests coming out showed no difference between sytem water and mains water.
 
Baxi combis are fitted with a filter in the return iso valve.

Okay I cleaned the filter on the cold water inlet tap. Pretty clean actually. I suspect though that you may be talking about the filter in the restrictor in the hydraulic inlet assembly under the hall effect sensor?

If so, I have a Baxi Duo-Tec Combi 40 HE, I don't think the 40 models have a restrictor.

Please correct me if I'm wrong or if I'm misunderstanding you or I have overlooked something.
 
The cold water filter you have cleaned is the one directly below the hall sensor....Which is the wrong strainer ;)

The far right iso valve which is the CH return valve (22mm) is the one that houses the return strainer. This is very simple to clean, once the boiler is empty, but may need the removal of the filling assembly if the Baxi kit has been fitted.

Mick
 
The cold water filter you have cleaned is the one directly below the hall sensor....Which is the wrong strainer ;)

The far right iso valve which is the CH return valve (22mm) is the one that houses the return strainer. This is very simple to clean, once the boiler is empty, but may need the removal of the filling assembly if the Baxi kit has been fitted.

Mick

I'm not a boiler engineer but I do have the boiler and the manual in front of me and what you are telling me doesn't seem to relate to either.

The hall sensor (AFAIAA) sits on top of the hydraulic inlet assembly, which is nowhere near the filter that I cleaned. Although I think I said that I didn't think it was the one you were referring to.

The rest of what you said doesn't seem to accord with the manual, or at least what you are describing doesn't seem to be described there ... and I have no idea what a baxi kit is.

If the valve is very easy to clean could you perhaps explain where it is and how I do that, or if it is in the manual and I am missing it, tell me where to look?

http://www.baxi.co.uk/documents/7219665-01_Duotec_HE_A_ErP_Install.pdf
 

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