Wonder if anyone can advise please. i've been reading till Im dizzy the fine art of balancing my system and every day I find myself with my digital thermometer re adjusting the flow and return to each rad. Just as I get it absolutly perfect (20 degree c differential), the very next day its circa 12 to 15. Anyway, my heating is brilliant as a result of all the tinkering and works perfectly but being a perfectionist, i've been reading further that my Vaillant EcoTec 630 should have a flow & return temp differential to the boiler of 20 degrees c in order for it to work efficiently and condense. My question rather than problem is how critical is this differential at the boiler given that my system works A1 perfectly and the rads vary in flow & return differential between 12 and 20 degrees but the rooms that need more heat have the lower diff so it actually suite my layout. Any responses greatly appreciated. From a perfectionist!!!
dont worry about it if the rads are warm and they are equaly warm (so u dont have some burning hot ones) then it will be fine your be there for days and weeks trying to get 20 c
Hi T'Barber, what are the actual flow and return temps at the boiler? I don't quite understand why the manufacturer states it as a 'differential', as afaik it's the return water wot does the condensing. So, the figure that matters is the return temp, regardless of wot the flow is doing. Anyways, assuming your boiler has a CH output control, try and have it as low as possible whilst still heating your house properly - the cooler the return water, the more it'll condense. Do you know if a exterior temp sensor thingy is available for your boiler? If so, it's worth getting one; it'll automatically modulate down your boiler according to the exterior temp and therefore how much heating your house interior needs. This way, the boiler should only fire up as low as it needs to deliver enough flow. If you can't get one of them, then it's worth adjusting the boiler output yourself every month or so to suit the ambient temp - keep it running as low as possible.
thanks Teuchter ok just measured them and this is normal operation i.e the heatings been on for a couple of hours. Ive fired up the boiler for a few minutes, the digital gauge on the front of the boiler is set to max (reading approx 65 at that point) the flow is reading 50 c and the return 35 c. When Ive done this before however and had the boiler running for say 15 mins plus flat out, the reading seem to be much closer maybe on 10 c difference.
sorry forgot this bit "Do you know if a exterior temp sensor thingy is available for your boiler? If so, it's worth getting one; it'll automatically modulate down your boiler according to the exterior temp and therefore how much heating your house interior needs." yeah got that but tend to turn it off as i've got an old draughty house with really high ceilings and to be honest, when its cold and the boiler starts to modulate down, it just doesn't feel warm despite it reaching temp. I now its a bizarre thing to say but thats the way it is. the rads need to be hot to keep the temp up. With it on modulating mode the boiler kicks in every 30 seconds / minute. With it off, it only comes on every few minutes. Can't see how its more cost effective.
Hi T'Barber. The outside temp sensor is meant to increase your boiler output flow temp in cold weather, and reduce it in warm. Ie: it should provide what's needed, but try and keep the flow temp down when not. The lower the flow temp, the lower the return. And it's the return that determines how effectively your boiler condenses - the lower the better. If you boiler return is genuinely only 35oC, then that is very low and your boiler will be very efficient. If your house is warm with this, then great stuff. If you don't have the external sensor working, then make sure that you manual;ly turn the output down as the weather gets warmer, or else you'll find your return temp in spring etc will be much higher - reduced efficiency.
thanks Teuchter I've made a mistake however as my room stat is a VRT 360 and has the facility to modulate from the 'room temp' dictating how hot the flow needs to be NOT an outside temp. Sorry. My mistake. thanks for the advice though. ill get the boiler up to speed, running it for say 30mins flat out and get a flow & return reading.
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