2 rads intermittingly go cold

[riversider]

Hello newbie here.
i have regularly had a rad that needed bleeding and when i got a additional rad fitted that one barely gets warm even though the trv is set on 5,but recently both rads have gone completely cold.I have read a few threads on here beforehand to help me.I closed off all rads at both ends and both problematic rads heated up,i then opened up the other rads around the house just a few turns on both ends of the rad(i only have one rad downstairs with a trv fitting).Everything was fine for a few days and then the same problem recurred again.I have microbore pipe going to the rads.

Should i try closing them off again and stupid question but do i need to close both ends,which i have been doing ?

I may in the future change the fittings to trv type,which end of the rad would it go on .I have looked at the diagrams of rad systems but i dont know which one i have ,i dont recall seeing any manifolds.

thanks for help

 

[simond]

One end will suffice.

The rads nearest the HW cylinder only need to be open a quarter turn.

TRVs are unlikely to resolve your problem, have you thought about changing the pump. Nice DIY job - if the isolation valves work.

 

[riversider]

Thanks for the reply simon.

One end will be suffice ,i wish i asked that last time it would have saved some of my skin on my knuckles

I will close all upstairs rads off then open them a 1/4 of a turn and give that a go.

Do you think it is a pump problem simon ,or could it be the micro bore that is the problem?If its the mbore i will just have to put up with it.How much does a pump cost ,at present i have red grundig type,my boiler is an appollo.
thanks

 

[simond]

Pumps don't tend to last so long on ubore because they are working against a higher resistance.

If you had another radiator fitted, was it by any chance just connected to the nearest existing one? If so, that is not going to be very successful.

A Grundfos pump would be a good choice, Screwfix can offer next day delivery on a boggo UPS 15-50 (www.screwfix.com), alternatively a shed will probably have one (Screwfix are the same company as B&Q, but not the same price).

If your bath rad is plumbed to come on with CH or HW then this could also be closed down a bit.

 

[riversider]

cheers simon.
yes i think the new rad fitted in the extension was just coonected to an existing one.
I currently have a grundfos ups 15-60 pump not a grundig one as i posted in the first thread.Can these pumps still work and be less effective than when they are new and could i tell rather than shelling out on a new pump that may do the same job.
i have closed one end off completely and turned down the other end to a 1/4 turn on every rad ,i will switch the heating back on in a few hours when it gets cold and start from there.


Appreciating your input simon.

thanks

 

[riversider]

this grundfos super selectric pump on the screw fix advert says it has 3 speeds ,do you know whereabouts on the pump to change the speed,maybe its that ?
http://www.screwfix.com/prods/67637...umps/Grundfos-15-60-Domestic-Circulating-Pump

 

[riversider]

i closed one end on all rads apart from the dodgy two and nothing happened ,so i closed off the other end on all rads and still no heat to the two cold rads,can anyone shed any light on the problem please.
Again i am not sure if you can change speed on your pump.
thanks

 

[riversider]

can anyone else help please

i dont know how to increase my pump speed ,if it is possible at all,but on the front it has a slotted piece and it is angled at 10 to 4 so i am not sure if firstly that is the speed and secondly if it is ,is it on max.
thanks