Greetings All, new to this site. After years of problems from my Drayton Flowshare diverter valve, I have decided to switch to a two-pump set up. So, valve gone, replaced by a tee, two check valves and two pumps. I'm in the process of rewiring, and have noticed when checking, that the cylinder stat is passing full mains voltage when calling for heat, which is fine. When satisfied, I can detect no voltage as expected, but touching the output with a mains tester screwdriver lights the neon. There is no back-feed to this part of the circuit (indeed the pump and boiler wasn't even connected when I noticied this effect). Does anyone have any idea why the neon lights on what should be a completely dead wire when the stat is not calling for heat? The cylinder stat is earthed, and the neon lights whether it is connected or not. I have tried two different stats, and get the same result each time. Any ideas much appreciated.
Strange behaviour of cylinder stat
- Thread starter Ilovemybackboiler
- Start date
G
gasafengineer
Throw that neon driver in the bin & use a volt tester.................why not use a mid position 3 port instead of two pumps? , how are you going too wire these two pumps & what boiler are we talking about?
Hi. I have also used a volt meter on the output from the cylinder stat. It is showing mains voltage when calling for heat, and no voltage when satisfied, as expected. The room stat is doing the same, but differs from the cylinder stat in that the neon in my tester screwdriver does not illuminate when I touch its output when it is satisfied. So I am still wondering why it does light in the case of the cylinder stat.
Why not use a mid position valve? Because I am sick and tired of my current one going wrong all of the time. The rubber gaitor has failed twice, and the micro switches have died more times than I can remember.
The boiler is a Baxi 552 back boiler. It has been operating perfectly for many years now, and is still as quiet as the day it was installed.
Why not use a mid position valve? Because I am sick and tired of my current one going wrong all of the time. The rubber gaitor has failed twice, and the micro switches have died more times than I can remember.
The boiler is a Baxi 552 back boiler. It has been operating perfectly for many years now, and is still as quiet as the day it was installed.
Sorry, you asked how I am wiring the two pumps.
The pumps are easy; just from the output from the stats. The boiler is a bit more tricky. I have settled on a pair of relays (with contact suppressors). One relay coil will be energized from the room stat, and the other from the cylinder stat. Both outputs from the relays will go to the boiler. Thus the boiler will fire when either or both pumps are energized.
The pumps are easy; just from the output from the stats. The boiler is a bit more tricky. I have settled on a pair of relays (with contact suppressors). One relay coil will be energized from the room stat, and the other from the cylinder stat. Both outputs from the relays will go to the boiler. Thus the boiler will fire when either or both pumps are energized.
Quote:- Why not use a mid position valve? Because I am sick and tired of my current one going wrong all of the time. The rubber gaitor has failed twice, and the micro switches have died more times than I can remember.
Then use a Honeywell v4073 mid position valve and save yourself a lot of hassle. If you insist on this modification then Grundfos do a 2 pump unit which contains all the check valves.
Then use a Honeywell v4073 mid position valve and save yourself a lot of hassle. If you insist on this modification then Grundfos do a 2 pump unit which contains all the check valves.
Yes, I looked at the PumpPlan Twin Headed Domestic Circulator Pump, but it is an expensive piece of kit, and would not easily fit into my existing set-up. Two new pumps off a well-known on-line auction site and a few bits and pieces to complete the work has been a much cheaper option. I've completed the plumbing side of things, and am just finishing off the wiring.
Perhaps the Honeywell would be more reliable than the Drayton mid position valve, but I have decided that I don't want to continue with one, and the internet is full of reports of problems with the lot of them.
Further research suggests that the 'false neon' on the cylinder stat output may be due to capacitance, and that I can ignore it. Does anyone know this to be true please?
Perhaps the Honeywell would be more reliable than the Drayton mid position valve, but I have decided that I don't want to continue with one, and the internet is full of reports of problems with the lot of them.
Further research suggests that the 'false neon' on the cylinder stat output may be due to capacitance, and that I can ignore it. Does anyone know this to be true please?
F
Fredthefly12
Yes mate it could well be capacitance, but as suggested you need to get yourself an auto-range multimeter, that are available for just over 20 notes at any good electrical wholesaler.
Of course what you propose with the relay will work well, not a problem. But please ensure you do a polarity, continuity & mains test on your
control system. By the way Honeywell controls are no better than any other, they all get faults. Just that some muppets pay top dollar for Honeywell??!!
Many thanks for your reply Fredthefly12. Wiring now complete, checked out and working fine. In the end I used just one changeover relay so now I have a spare. Just have to remember to run the C/H pump now and again in the summer to make sure it remains in good order.
Your false neon could also indicate that the impedance of your "earth" on that section is too high or broken, which could lead to a very dangerous situation under fault conditions.
Checking this is not a diy job.
Checking this is not a diy job.
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