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ravenheat combi boiler rsf 820-20
- Thread starter edna
- Start date
Heres where I'd be looking
1. DV check as described but here it is again, my version, for those who missed it in the fog of previous posts
Boiler cold and set to HW. Turn hot tap on. If Flow pipe 2nd from right gets hot more than a foot or two away from boiler then it is robbing heat from the HW. If rads are warming up then the DV is a cert.
2. [Corgi territory = So I'm not going into too much detail] Check inlet and burner pressures. Undersized pipe, ECV not open fully, Sulphidisation in pipework and other blockages can reduce the amount of gas being burnt = Not enough heat to warm your water sufficiently.
2a. A control problem can also be indicated after gas pressure test
2b. Likewise a gas valve problem can be found after checking the voltage to and resistance of the modulating coil,[/Corgi territory]
3. Check flow rate. If taps run too fast then the water isnt hanging about in the boiler long enough to be heated up to the required temperature. There is an adjustment screw on the DV to stop water running through too fast!
Still getting nowhere? Poor heat transfer due to a thick coating of crud in the heat exchanger on the system water side and/or limescale on the DHW side would be suspect areas.
Its hard to tell from here of course what the culprit will be but if I had 50p Id bet on 2b
RSF 820/20 mainly have liquid phial stats, but I have in my possession some black thermistors for one of these. I am assuming; because I have never seen one, that before this model progressed into the RSF82 and 84 versions that some were made with fully modulating controls.
1. DV check as described but here it is again, my version, for those who missed it in the fog of previous posts
Boiler cold and set to HW. Turn hot tap on. If Flow pipe 2nd from right gets hot more than a foot or two away from boiler then it is robbing heat from the HW. If rads are warming up then the DV is a cert.
2. [Corgi territory = So I'm not going into too much detail] Check inlet and burner pressures. Undersized pipe, ECV not open fully, Sulphidisation in pipework and other blockages can reduce the amount of gas being burnt = Not enough heat to warm your water sufficiently.
2a. A control problem can also be indicated after gas pressure test
2b. Likewise a gas valve problem can be found after checking the voltage to and resistance of the modulating coil,[/Corgi territory]
3. Check flow rate. If taps run too fast then the water isnt hanging about in the boiler long enough to be heated up to the required temperature. There is an adjustment screw on the DV to stop water running through too fast!
Still getting nowhere? Poor heat transfer due to a thick coating of crud in the heat exchanger on the system water side and/or limescale on the DHW side would be suspect areas.
Its hard to tell from here of course what the culprit will be but if I had 50p Id bet on 2b
RSF 820/20 mainly have liquid phial stats, but I have in my possession some black thermistors for one of these. I am assuming; because I have never seen one, that before this model progressed into the RSF82 and 84 versions that some were made with fully modulating controls.
Thanks everybody for all your replies and the explanations. The plumber is coming Monday and is going to strip the DV first , to see if the inside is OK, and to check if a new one was fitted 5 weeks ago. Till then theres nothing I can do, I will let you know the outcome.
Edna.
EDNA, BE CAREFUL. THE PLUMBER THATS FUMBLING AROUND IN YOUR BOILER YOU SAID IS NOT CORGI AND SHOULD therefore NOT EVEN BE REMOVING THE COVER OF THE BOILER. HE MAY BE THE NICEST GUY ON THE PLANET BUT ITS WRONG TO THIS AND YOU HAVE ALREADY WASTED A LOT OF MONEY.
IF I WERE IN YOUR SHOES I WOULD CALL IN A RAVENHEAT ENGINEER WHO WILL KNOW THE BOILER INSIDE OUT AND WILL HAVE ALL THE SPARES IN THE VAN OR CLOSE BY.
ONE VISIT, ONE PART, JOB DONE.
BLESS YOU AND KEEP UP THE GOOD WORK.
NEAL
IF I WERE IN YOUR SHOES I WOULD CALL IN A RAVENHEAT ENGINEER WHO WILL KNOW THE BOILER INSIDE OUT AND WILL HAVE ALL THE SPARES IN THE VAN OR CLOSE BY.
ONE VISIT, ONE PART, JOB DONE.
BLESS YOU AND KEEP UP THE GOOD WORK.
NEAL
Hi again, At last I am able to give you information re this boiler fault, and you will not I think believe it. Firstly the plumber came with a corgi registered friend of his, they tested the gas pressure which was fine, water flow rate also fine, took off three way valve to check diaphragm OK , put on new DHW stat, stiil either cold or at best luke warm water. After scratching their heads, and a few mutterings of disbelief, they felt the DHW flow pipe on the outside of the boiler, and it was, as previous red hot, given this, they could not understand why it was not coming out hot at the tap. So, they decided to turn off the mains cold water feed to the boiler and drain the system yet again , then cut the DHW flow pipe and fix an isolation valve with a lenght of pipe attached, to simulate turning on any one of the domastic hot water taps. When they turned on the mains cold stop tap to supply the boiler, water started to come out from the remaining DHW flow pipe that had been cut , and left open, which indicated to them somehow water was entering this pipe and flowing to the boiler, which in fact it shouldnt, as this was the DHW flow which takes hot water from the boiler to the taps. They capped this pipe, and opened the isolater valve connected to the other section of the DHW flow, and low and behold when the water came out it was hot, and continued to remain so. This left the question of where was the DHW flow pipe picking up a cold water feed, the answer , wait for it, was from the bathroom shower, it would seem something had gone wrong internally with the shower mixer unit on the bath,and water was passing from the cold inlet pipe feeding the shower head and pushing water directly to the shower head hot water inlet feed even though the contols for the shower unit were closed. This meant every time you turned on anyone of the domestic hot water taps, the cold water feed to the shower which is under constant pressure entered the domestic hot water pipe, thru the inlet of the hot water feed to the shower head, stopping any hot water from flowing from the boiler, the cold water feed to this pipe was isolated, and low and behold I now have hot water, and have for the first time in many a day been able to have a relaxing bath, ( but alas not a shower. ) So thats it , can I thank those of you who took the time ,and the trouble to give help and advise, and I hope this experience may be of some use to someone in the future. And for the record the plumber and his corgi registered friend would not take any payment for what they had done , other than to charge me for the DHW stat. So, although having paid £529 previously only to be left with the original problem, by the ex BG engineer, I feel my faith has been restored as a result of your assistance, and that of the plumber and his friend. I hope you are able to understand all of this, as I have written down all of what was said to me by those two. Many thanks,
PS , does anyone know anything about a Triton Capella shower unit, bar mixer with integral diverter?. Description taken from manual, ( Diverter, not again, )
(ONLY JOKING). Edna.
To slugbabydotcom,
Showers may wet you but not when they dont work.
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