Cosd Posted December 18, 2009 Report Share Posted December 18, 2009 (edited) For any plumbers on here, a brief summary: Vailant Boiler EcoTec Plus 637 Vailant Presurised cylinder ( Megaflo type, can't remember model number) Vailant VRT360F (remote thermostat and control Brief history, system 6 months old, was working fine until I needed to move 1 radiator 6" across. Switched off boiler then emptied system; Opened bleed valves on the radiators starting upstairs, then opened downstairs as well until water emptied and stopped running from the release valve. Odd thing, having removed the radiator that we were going to move, the water remained in the pipes it would no go down, even though the release valve had stopped running. We had to empty the pipes so we could we could cut and weld new pipes further along. To empty the pipes we had to blow down both pipes and after a long struggle we managed to get enough water out to allow us to weld and refit the rad. Refilled system, and bled all the rads starting downstairs working my way upstairs. Presurised the system back to 2.0bar and switched the boiler back on. It fired up and I could feel the pipes getting warm. That was about three weeks ago. Problem: Ever since the work I did, the downstairs of the house just doesn't get hot. Most the rads get luke warm whereas the upstairs rads heat strongly (all valves set the same on all rads) and the rad we moved and one other has absolutely no heat at all, stone cold! The rads have been bled, I let water come out into a container for a minute or so on each rad, still no joy. Today I switched all the valves off upstairs and downstairs except the one I moved, I opened the bleed valve and after half hour or so of emptying cold water, hot water eventually came out (no air) and I thought I cracked it. Opened other downstairs valves and heating was strong. I reopened the upstairs rads and they heated up but the downstairs went luke warm again and the same two rads stone cold...................... Sorry for the long winded explanation I just wanted to give you all the detail, but I'm out of ideas......... Can anyone offer any ideas please? Cos Edited December 18, 2009 by Cosd Quote Link to comment Share on other sites More sharing options...
ST3V3 Posted December 18, 2009 Report Share Posted December 18, 2009 not a plumber but sounds like the system needs balancing the rads that are red hot turn the valves down a bit and the cold ones up until they all reach the same temp Quote Link to comment Share on other sites More sharing options...
Cosd Posted December 18, 2009 Author Report Share Posted December 18, 2009 not a plumber but sounds like the system needs balancing the rads that are red hot turn the valves down a bit and the cold ones up until they all reach the same temp Tried upstairs rads on 3 and downstairs on max (6), upstairs cooled down, downstairs hardly a difference. Before problem started, up and down on max, all rads burning hot... Quote Link to comment Share on other sites More sharing options...
libs Posted December 18, 2009 Report Share Posted December 18, 2009 We had big problems after we had some work done, sludge in our dowstairs rads, do they feel the same temp all across or is there a, for want of a better phrase, pryamid of cold across the rad? A days powerflushing sorted ours out. Quote Link to comment Share on other sites More sharing options...
Slug Posted December 18, 2009 Report Share Posted December 18, 2009 Not familiar with this boilers internals, a couple of things occur to me 1) Do all the rads have TRVs on them and does one have no TRV's ? A lot of modern boilers have internal bypass, some systems run a rad with both valves always open..are the Thermostatic valves screwed right down with the special cap ? also where is the boiler in relation to the highest section of pipework ? If you have high level pipes there may be bleed valve there, air locks are less common on high pressure systems and more common on F&E systems but you can get them Quote Link to comment Share on other sites More sharing options...
al4x Posted December 18, 2009 Report Share Posted December 18, 2009 an you feel the main supply pipes at the downstairs rads are they hot? Otherwise sounds really odd, I've done a lot on our system and put new rads all over the place and without balancing so far they all get hot no problem, sounds a little like a TRV issue or the valves at the other end of the rad but does seem a bit peculiar with a modern boiler Quote Link to comment Share on other sites More sharing options...
Plumbob Posted December 18, 2009 Report Share Posted December 18, 2009 Sounds like an airlock somewhere, Have you bled the air from the pump? if its a system boiler(internal pump and vessel) the air valve is on the pump block and has a dust cap which needs to be just open to let air out. If the pump is in the cylinder cupboard undo the slotted center screw a turn and see if you can get some air out. Myzeneye will be along shortly, if I remember rightly hes quite hot on Vaillants. Quote Link to comment Share on other sites More sharing options...
davecooper1 Posted December 18, 2009 Report Share Posted December 18, 2009 Sounds like an airlock somewhere, Have you bled the air from the pump? if its a system boiler(internal pump and vessel) the air valve is on the pump block and has a dust cap which needs to be just open to let air out.If the pump is in the cylinder cupboard undo the slotted center screw a turn and see if you can get some air out. Myzeneye will be along shortly, if I remember rightly hes quite hot on Vaillants. Have to agree, youve got airlocks in your pipes, in my opinion. Quote Link to comment Share on other sites More sharing options...
Plumbob Posted December 18, 2009 Report Share Posted December 18, 2009 Yep it is a system boiler, any air bleeds on the flow to the heating where it splits between thre hot water coil and the heating? Quote Link to comment Share on other sites More sharing options...
lewis Posted December 18, 2009 Report Share Posted December 18, 2009 (edited) Im a 2nd year apprentice plumber but im still learning... Sound's like you need to Balance the system using the Lockshield (at the bottom left of the radiatior), The hottest radiatior's in the house should be turned down to nothing and opposite for the coldest. Let us know how you get on. Edited December 18, 2009 by lewis Quote Link to comment Share on other sites More sharing options...
Yellow Bear Posted December 18, 2009 Report Share Posted December 18, 2009 Needs Balancing as well as possibly having an air lock Go to the hot rads and close the valve that does not have a permanent handle (lock shield) fully then back off half a turn. When the temperatures have settled go to the hotest 50% of those not turned down - close fully and back off 1 full turn. This would normally do the trick - but fine tuning on these valves can take a few days. Technically the "authority" on this type of valve is mostly in the first full turn open from the closed position that is why you start with closed. Air lock is another problem, and without viewing the system I would be loath to advise. D Quote Link to comment Share on other sites More sharing options...
Cosd Posted December 18, 2009 Author Report Share Posted December 18, 2009 Sorry guys, had to go away from the pc, but thanks very much for the sugestions so far. In answer to some of the questions: * I doubt very much it is a sludge problem as the system is less than 6 months old, everything brand new inc pipes * The rads which are luke warm are luke warm all over, no pyramid effect * The two rads that don't heat up are not hot on any pipe * All rads fitted with Drayton TRV4 valves I think I understand when some people have mentioned balancing, so you turn down the flow on hotter rads and turn it up on cooler rads, this way the temp gets even around the house. But, before I moved the rad, everything was full open, no balancing, and every rad was really hot. So though I can understand why balancing is a good idea as a fine tune, there is an underline problem which has happened in this case which I think needs addressing first. The pump is internal to the boiler, but I was told by Vailant that it self bleeds any air!! I'm not a plumber but I can't help but feel there is air somewhere in the pipework, and I think it is related to when we drained the system and there was still water in the two pipes for this particular rad! In case anyone is wondering why I don't call the people who installed it; The Corgi plumber was assigned by the building firm I was using to extend the house, the builders left the job unfinished and went bust shortly afterwards. I don't have contact details of the plumber nor the name of his firm. Quote Link to comment Share on other sites More sharing options...
magman Posted December 19, 2009 Report Share Posted December 19, 2009 What i would do is close the valve's on the two rads that are not working , remove both rads . make sure the heating has been on for a while then turn the boiler off , open one of the four valve's at a time pulling at least two buckets of water though each valve . you should pull air though at least one of them . replace the rads , open valves and vent . then turn the heating back on . Quote Link to comment Share on other sites More sharing options...
Blackpowder Posted December 19, 2009 Report Share Posted December 19, 2009 Just read this before I am out the door. If it ias a new sealed system sludge should not be a problem. Try this switch of system so pump is stopped:- Shut down RH radiator valve then let lots of water bleed through the air valve Shut down LH and ditto. Perhaps you have had this reply already but had not time to read all posts. Blackpowder Quote Link to comment Share on other sites More sharing options...
PWD Posted December 19, 2009 Report Share Posted December 19, 2009 Could be a similar pro I had once ...best way to check its not a flow issue (best description I have ) but turn off all the rads in the house both sides.....turn on heating for 5 mins..then turn on the rad you moved only ...see if it gets hot ..if it does then every 5 mins turn on another starting at ground level ..make sure your combi pressure is at 2 bar or above for this ....if this dont work turn them all off again except for the one you moved and bleed it at least 3 pints ..keep the combi pressure up though...It can happen though rare that the hot water is stubborn aginst flowing to a part of the system if there are lots of tight bends or Tee,s in an opposing direction so the flow keeps going in one direction and missing the turns so to speak Quote Link to comment Share on other sites More sharing options...
Cosd Posted December 19, 2009 Author Report Share Posted December 19, 2009 (edited) OK guys, I think it's sorted. Big thanks to everyone taking time out for me on this one. Usually on these types of threads the outcome is left out and people never know what happened, so I wanted to write this in case anyone else has a similar problem. So in a nutshell, two rads downsatirs were stone cold, and some others downstairs were luke warm, whilst others are baking. I didn't say this in my initial post but just to give you and idea of the size of the system, 10 rads downstairs 8 rads upstairs. I switched off all the rads upstairs using left valves (not TRV's) and all the rads downstairs barring the two which were stone cold. Within moments hot water came into both rads and they heated up very hot Then I switched on the luke warm rads downsatirs and they got very hot :o I don't know if this has helped, but I checked the presure in the boiler and it was 1.9bar which I presurised it to on recomendation by a Vailant plumber as it's optimum presure; But before I moved the rad I always kept the presure on 2.3bar. My mind told me that if there is more presure, the water would flow quicker and hopefully the heated water would travel faster round the system, hopefully all the way round all the rads! So I upped the presure to 2.3bar. Then I went round all the upstairs rads, and gave the valves 2 full turns from closed position. After a short while some rads were very hot and others moderate, so I gave those rads another full turn towards open. Final result, all rads in the whole house baking. I don't want to say I'm out of the water yet, as it's success will be tested when the timer switches the system off and all the rads cool completely before coming on again. If they all work then, then it's job done......................I'll let you know. Cheers lads!!!!!!!!!!! Edited December 19, 2009 by Cosd Quote Link to comment Share on other sites More sharing options...
myzeneye Posted December 20, 2009 Report Share Posted December 20, 2009 sorry i didnt help ! ive been away pal visiting parents for christmas... glad you got sorted in the end.... firstly, your pressure is now too high mate. when the system gets daft hot your pressure relief valve (prv) WILL blow off at 3 bar. your only allowing 0.7 bar for expansion and when water gets hot it really does expand, especially in a sealed system. this can cause all kinds of issues , not to mention the undue stress on ALL components, joints,valves,prv passing wich will lead to a load of props if not dealt with etc etc.... in short, let the system cool down to cold, read pressure gauge and then release some c.h water from a drain cock untill pressure reads 1.2 bar. in addition, another reason for doing this is economy. if there is more water in the system then it will take more heat input to get it up to temp. having that extra water content will use more gas, effecting efficienecy. this is why they came up with the idea of micro bore pipe in the 70's/80's..(awfull stuff) the thoery was the less water content the less fuel required to heat it. so, get that pressure droppped before you have a joint blow, pump strain it self to death, prv blow or start to pass, or any number of other problems.......... hahaha the problem you had, as you sussed eventually was an air lock. the problem most diy'ers have when trying to shift this is the understanding of what is going on. to be fair, some "plumbers" do aswell..... hahaha most folks on here had it sussed, but the advice on getting rid varried in places....the key is getting the air out of the flow and return seperatley in their own right.... for the future, here it is. turn heating off and ensure pump has stopped ( some system have "pump over run)... turn off both valves on the problem rad fully closed. using a spanner, undo one of the valves from the rad, i use a ruble sack under the valve to catch the small amount of water wich comes out. NOW, because both valves are closed, the water in the pipes stays put. the water in the rad aslo stays put because there is a vacum.... (if you opened the bleed nipple it would let air in and the contents of the rad would come out into the rubble sack. now put the rubble sack around the rad valve and pipe and open the rad valve a bit..... water will gush out into the sack and a glug of air should come out with it. when it does close the valve and re-attach it to the rad, nice and tight. do the same on the other side. crack nut off on the 2nd valve, with empty rubble sack underneath... catch the 1/2 pint of water wich should stop as soon as the vacum takes a hold.... when it has, open the 2nd valve into the bag and allow it to run water untill you get the splutter of air through.... reattach.... open both valves and bleed the rad... it shouldnt need much bleeding if any.... but the 1/2 pint you lost creating your vaccum will replenish from the flow and return pipes when you open them and a small amount of air should make its way to the top of the rad for you to bleed out.... this should cure your issue.... youve cleared BOTH the flow AND the return... check system pressure and top up if neccisarry...turn on heating and check operation. this works most of the time but sometimes, due to poor installation airlocks can be **** and rquire back filling from mains etc etc ... but for anyone with this problem in the future, follow these steps and you should be sorted. you can also use this vacum method for other jobs like removing a rad without spliing a drop....close both valves, crack off one side from rad and have rubble sack under to catch the bit of water ( not allot)... when the pressure squirt has stopped you can reposition the bag and then open the bleed nipple on the rad...this will drain the rad into the bag nicley and under control without spilling a drop. when it stops, undo the other side and remove the empty rad. creating vacums is a trick of the trade, bung kits are often used to plug open vents and f&e pipes to allow siezed pump valves to be opened, 3 ports to be swapped, rad valves and trvs etc etc (although any good plumber will succsessfully "snatch" these...) finally, system balancing should not be under estimated.... it can make huge differences on a systems efficiency.... other folk on here like magman,yellow bear had it right (of course) but i often find being in depth and helping somone undertsand what there doing makes all the differance... any one has a problem i will always try my best to get you sorted... happy xmas folks.. matty Quote Link to comment Share on other sites More sharing options...
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