Question about Hardware & Accessories
Re: siemens boiler rwb9 controller problem. I moved into a new house and this boiler is driving me crazy... the controller seems to be working fine. has got all the lights in right place as I programmed but the heating is not on. even when I set HW and CH as 'on' it won't work. On the wall, I have a the thingy for setting the temperature of the house but as I turned the nob still boiler is CH is not starting.
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Posted on Jan 02, 2017
thermostat on the gas valve needs to be replaced,, which you will probly have to change the hole gas vale ,, check on the parts and labor and if it is over 6 years old wheigh the diffrence between it and a new unit good luck
Posted on Jun 10, 2009
SOURCE: Combi Boiler gives CH but not HW
Combi boilers have many moving parts compared to conventional models so must be serviced annually to prevent breakdowns.
Your boiler most likely has one of four problems:-
1. When the receiver for the wireless thermostat was fitted, other wiring was loosened and has come adrift. It's a possibility, but in my experience unlikely as the wiring involved isn't anything to do with HW supply..
2. During receiver fitting the pcb suffered a static electricity surge. Possible, but unlikely as this sort of damage is usually immediately evident. However, boiler pcb's are notorious for sudden failures anyway and can happen anytime. Combi pcb's are more prone to fail as they usually have up to four solenoids fitted and these do eventually fail due to mechanical wear.
3. When you your combi is in CH mode it heats the primary water circuit and directs the flow through the CH heat exchanger. When you open a hot tap (US=faucet) you're opening a supply of cold water initially as there is no stored hot water like in a conventional system. As the water starts to flow through the combi's diverter valve there's a pressure drop which activates a rubber diaphragm with mechanical connections to other parts. The diaphragm is one part which is routinely replaced annually as it will eventually fatigue and fail with the symptoms which you describe. In addition, the mechanical parts connected to the diaphragm pass through various seals in order to activate at least one micro switch. If the seals fail then the moving parts eventually corrode and seize up. Regular servicing prevents this. Combi seizures are a very common complaint in hard water areas.
4. One of the micro switches activated by the diverter valve has failed. Possible, but not likely. The purpose of the switches is usually to fire up the boiler to provide HW when the CH is not currently running, but as you haven't said which Vaillant you have I can't be definitive on this.
One major problem with combi boilers is that multiple failures can and certainly do occur almost at once. Unmaintained units may appear to be correctly functioning but in reality a number of worn parts can be close to failing. When one part fails, the others can't cope with the stress and fail as well.
In most civilised countries including the UK it's a criminal offence to attempt most repairs yourself unless you're qualified to work on gas appliances, so you need to find a decent heating engineer to service your boiler (ask your new neighbours). In the UK you can expect to pay around £120-£150 annually for a routine boiler service. If the circuit board has failed then it can easily add over £100. If parts inside the diverter valve/manifold have seized then you can be looking at an additional £80-£150. Note that diaphragm failures on their own do not merit diverter/manifold replacement and that if you have a new diverter fitted then a new diaphragm will already be present inside.
Dishonest heating engineers always diagnose a failed pcb as they know that you have no way of knowing whether it's true. If you can live with the problem for a few days then failed pcb's are usually a straightforward repair and there are plenty of companies who will send you a guaranteed exchange unit for much less than the cost of a new one. As long as you are not opening the main boiler casing which houses the combustion chamber and gas valve assemblies then some territories allow non gas qualified replacement, but others insist that the work is done by a qualified electrician: this is not the case in the UK as long as the pcb is not connected directly to mains electricity (no modern domestic ones are).
Posted on Oct 13, 2009
You definetly have a control issue. However trying to diagnose the exact problems that you have would be very difficult without actually seeing the wiring. You defintely have a wiring/control issue but I cannot tell you exactly what it is without more info. Sorry, I would love to help you more...
Posted on Nov 13, 2009
The original timer either was a mechanical wind-up clock or it used a "power stealing" circuit to keep itself powered while it was turned on. The new timer doesn't have this feature. While the light bulb is off, it can run on a small amount of power drawn through the light bulb, but when it turns on the bulb, there is not enough voltage left to keep the switch electronics powered, so when its power supply capacitor runs out of charge, it can't keep the bulb turned on. It probably also forgets its settings.
The only (safe) way to use this model is to bring in a neutral wire. The timer should be connected as follows:
Black: connect to house black from panel (always live when breaker is on).
Red: connect to house black from light fixture.
White: connect to house neutral (white).
Green: connect to house ground (bare copper or green).
If the wires in the box come from one of the porch lights through a conduit (this seems likely; I don't think there are any other legal methods that would leave out the white wire), then it should not be too difficult to add the white wire. Tape a pull string to one end of the wires and pull them out of the conduit at the other end. Bundle a 14 gauge white wire with old wires (tape it to the pull string) and mark the black wire that goes to the light bulbs at each end so you know which one to connect to the red timer wire. Put some wire pulling lubricant on the wire bundle (it will probably pull a lot harder with the extra wire) and pull it all back into the conduit using the pull string.
Note 1: It's tempting to just push the white wire in with the others remaining in place, but it will probably jam when it runs into a place where the others twist around each other, most likely at an elbow in the conduit. That might damage the insulation of the other wires.
Note 2: 14 gauge is the typical size for a residential light circuit. Use the same size that's in there now, and be sure it is a type UL listed for residential power wiring. Look for the fine print on the original wire; you should be OK if you match that. If more than half of the conduit cross-section will be filled with wire when you add the neutral, consult a licensed electrician to be sure you won't have a problem with crowded wires overheating.
Note 3: An alternative is to use the original wires to pull in a 14-3 cable (black, red, white and ground), provided the conduit elbows have a large enough radius to let it go through. However, the jacket on this cable has considerably more friction than the insulation on wires typically run through conduits.
What happened to the original timer? Maybe we can figure out how to fix it more easily than rewiring the box. I know there is at least one two-wire electronic timer on the market, but I'll have to go over to my church and look up the brand and model. Check back after 7:30 pm CST Oct. 13, 2010.
Posted on Oct 13, 2010
Testimonial: "The white was tucked in the back of the box and painted over so I didn't see it. By connecting as you suggested it woks just super. Thanks"
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