General > General Technical Chat

[ElectroBOOM] Valve motors inefficient design or fail-safe construction?

<< < (3/4) > >>

floobydust:
24VAC the circuit, thermostat and wiring is low voltage Class 2 energy-limited and no fire or electrocution hazard. Same for doorbell circuits. i.e. transformer https://www.hammfg.com/electronics/transformers/class-2/ba-c-d-e
Why would you need two tradesmen, plumber and electrician to replace one. Is that how it is in the UK? Sounds expensive.

Common here is Honeywell V4043 which have been around since 1965. They can last 20 years no prob. You can buy a replacement motor/gearbox or ball/o-ring if you're into repairing them but tradesmen just replace the whole thing for max profit  on the callout. The valve's claim to fame is long life because the ball rotates with every open/close cycle and wears evenly. If you have a lot of trapped air in the system the oxygen apparently deteriorates the ball.

NiHaoMike:

--- Quote from: tom66 on May 07, 2022, 09:52:27 am ---Complaining about 9W of power dissipated in the motor for a heating system that's probably supplying 2-3kW per room - and only supplying that when the zone itself is on - seems like Medhi cannot see the forest for the trees.

--- End quote ---
Those few watts per zone add up if it's desired to run the heating system on battery power. I guess it's safe to assume that such elaborate heating systems are installed in areas where they'll actually be used for a good part of the year, and by extension, winter storms are not uncommon in those areas.

--- Quote from: floobydust on May 07, 2022, 05:06:51 pm ---There is no decent "fail safe" system for hydronic heating. It's just people following some old convention.
Zone valves can be normally open or normally closed. The normally open valves require constant power to stay closed, the normally closed valves require constant power to stay open. They have a spring return. Really old zone valves were motorized both ways, with a limit switch at each end. They wouldn't help because a closed valve will just stay closed.

--- End quote ---
Normally closed but with a set screw to keep it open a little when "off" would be a good compromise. Or perhaps have a valve that's normally half open, with one polarity to close it and the other polarity to open it?

HwAoRrDk:

--- Quote from: floobydust on May 08, 2022, 12:19:54 am ---Why would you need two tradesmen, plumber and electrician to replace one. Is that how it is in the UK? Sounds expensive.

--- End quote ---

No, only a single tradesman. Such work is typically done by a 'heating engineer', who is certified to work with gas as well as does the plumbing and electrical.

I'm not totally sure whether they're actually required to be certified in the same way that electricians are, possibly because a heating system may be treated like any other electrical domestic appliance as far as regulations goes.

Everything on your typical UK central heating system runs at 240V - valves, thermostats, etc. - I think because before the arrival of sophisticated digital control systems, control would be achieved by connecting things in series. Look up "s-plan wiring diagram" for an idea.

elekorsi:
I still don't understand why should there be any failsafe state on such simple thing. If the power fails the boiler will shut down and the pumps will not run, so why would there be a need for the failsafe state of the valves? If freezing is such a problem, the system would also need redundant pumps, so if one fails, the other one kicks in...but we are talking here about house central heating and not some multi MW steam boiler...

Siwastaja:
Besides, these motors are engineered to save every cent in manufacturing. They could easily just spend $0.20 in thicker copper wire, which could halve the consumption without having to make any major changes. This would also stop the motors from failing early as the windings would run cooler. But there is no incentive to do that.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod