Rads take ages to warm up

15 Jun 2010
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United Kingdom
Just fitted new pump, new pcb to boiler and new 3-port mid-position valve. Just emptied and refilled with clean water and fernox flush, and all "sounds" to be working okay (although having to bleed air from bleed point in airing cupboard loads when h/w is on). Rads taking ages to heat up (15 mins and downstairs rads only very lukewarm) Any ideas how long it "should" take, and what might be the problem?
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What boiler,what temp setting and how long does the burner stay on b4 shutting down by boilers stat.Flow and return temps?
Boiler's a Baxi Solo 3 and it seems to be working fine. Not tripping out for any reason, just cycling on and off as I'd expect. At the water pump, the water in the pipes is nice and toasty hot, as indeed it is as it passes through port A and/or B depending on where the 3-port valve is pointing. A couple of upstairs single rads are quite warm, a couple of others are rubbish almost stone cold. I've checked all the rad valves, and bled them all as they refilled with water, so water must be moving into them albeit probably very slowly. Downstairs rads are almost cold. Starting to think there's a blockage somewhere, or restriction at best, but how the hell can I identify where without dismantling the house (with wife and 5 kids living in it !!)
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Well, all I can say is ... when your TV breaks ... GET IT FIXED ... it's a false economy leaving it a while :LOL:
Whilst I give it some thought, it might be possible one or more rad valves are blocked or restricting - is that a common problem?
Have you 'played' with the rad valves? It might be a case of balancing the system. If you turn off the hot rads then the cold ones should come on, if this is the case then balancing it is. You can find how to do it in the FAQ.

Ahhhh ... makes sense ... will try now and feedback ... thanks for your advice, much appreciated :D
Also, the boiler's overheated and cutout a couple of times. The thermostat is set to 3 of 6 which is about mid-way. Perhaps suggest a restricted flow to take away the hot water? Have shutoff the upstairs rads, waiting for a few mins now to try the "balanced rads" idea ...
For the boiler to cut out means you have air in the system.

Turn off central heating control and leave hot water turned on. Bleed any air vents in air in cupboard. Turning pump speed up and down will force any air up to the bleed valve. You can normally hear the air moving around. Once that has been done turn off the hot water and turn on the heating, turning the pump up and down again forcing the air round to the rads. Then you can go round and bleed them again. Also don't forget to bleed the pump.
Once complete set the pump to its original setting.

Good call, will do now and report back ... thanks again for your valuable help, I really do appreciate it.
OK ... THIS IS SERIOUSLY STARTING TO GET ON MY T*TS!!! Is there an easy way to identify a circuit diagram of the plumbing, from the pump onwards ... i.e. to which rads, whether its a single feed/return or dual, etc. as some rads work, some don't at all, some are lukewarm after 2hrs of running. The boiler pops every now and then, and I've bled it sill, so it surely must be flow restriction, causing the boiler to self-check and overheat, thus it popping, and perhaps explaining why some rads work and some don't. The downstairs rads - there's only two - one's mediocre the other's lukewarm at best. It all used to work okay a while back, then the bathroom rad stopped working and I assumed it was one or both of the valves. When I checked today (after flushing) it turns out the valves are okay. Now its fitted on a laminate floor - i.e. right ol' mess and hoo haah to remove and check pipe under the floor, but I'm sure I recall when the floor was up that it was the same pipe going past both valves with Ts in. Please, I beg, on bended knee, at risk of doing a whole crate of wife basher if I don't get even a small win today ... I've spent tons just before crimbo on stuff that's made little or no difference ... AARRGGHH
and to top it all ... the bloody boiler's popping overheating almost every few mins now. Is there anywhere on the Baxi Solo 3 that I can bleed, or is the bleed in teh airing cupboard it?
Have you fitted your 3 port valve correctly, A port to rads, B port to cylinder. ;) ;)
Hi are you are sure you haven't got a pressure system with a loop as if you are bleeding you are losing its just taking in the Air and not letting it out do you have header tank in loft. you saying the boiler is cutting out makes me think that you have,also some plumbers who fit heating never regulate the none therm valve, that should be done when first set up then you put on screw cap so it can't be turned on or off,

do you have an open rad with no therm valve i checked mine the other day and found they had put it on full both sides so losing a hell of a lot of heat, my main proberlem that I have get to get sorted is had new rads and boiler and tank, but old pipe was used which is in the concrete floor, boiler pipe is 22mm but that goes into floor which is 1 inch not clever, mine is takeing 2 hours to heat up, i am going to change all my pipe work in floor and drop 10/15mm to the rads from the 22mm and as we have very long runs of up to 50 meters of 1 inch i think i would save 35% of my oil and rads should heat up in 5 to 10 mins which is more like it, Im not a plumber but done a year as my first job in the early 70s, when CORGI meant you just used there gas but I rember all the basics,

Good book to get is Readers Digest Book on Heating from Amazon or ebay that tells you all you need to know all the best Tony. :mrgreen:

PS one thing not to sure about my self is 10 mm or 15 mm when i was doing it i was putting in 8 mm pipe long time ago was good at the time off a maifold work well,

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