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ON/OFF switch for circulators. Allowable? Type to use?
in Gas Heating
I have 4 Grundfos circulators on my heating system. When one goes, every few years it seems, it makes a helluva noise. If it's in the middle of the night, I can't get a plumber right away, or don't want to pay off-hour rates. To get rid of the noise I have to shut down the whole system. What I'd like to be able to do is shut down the bad circulator only, until I can have it replaced. Can I wire up a simple switch, one per circulator, to do that? Any code issues? What type switch would you recommend? Today I opened up a little electical box and unwired the bad circulator, but I'd like to make it easier, in case it happens when I'm out and my wife has to stop a circulator from squealing.
Yes. You can install switches.
The rule for switches electrically because they are considered a motor circuit is as follows:
1. The switch should be rated in motor horsepower so a circulator rated say 1/8 horsepower should have a switch rated no less that 1/8 horsepower. simple enough. the switch may have a higher rating.
2. not all switches are rated in motor horsepower. If the switch is not rated in horsepower, it must be rated for double the motor amperage. So a circulator rated 5.0 amps must have a switch rated for at least 10 amps.
In reality the amperage/horsepower of most "residential circulators" can probably be wired to any 15 or 20 amp toggle switch that you would get at a hardware or big box store. A standard wall type toggle switch of the same style used for lights is fine.
If it was my house I would use 20amp rated switches there just a little heavier and will last longer even though they don't get used much.
The real question is , why are your circulators failing?. I would suspect iron particles in the water if the bearings are failing.
Does your system use a lot of make-up water?? Any leaks??
you already have a switch wired in and installed in your home!!
The thermostat is the simplest switch already there. If the circ becomes noisy or an issue and it is unbearable, turn the heat off.
The end result will be the same if you were to wire in your own line voltage switch......1. the problem with the circ stops and 2. you will have no heat until resolved.Dave H-1
I like a simple switch on circulators. Not only does is solve the issue that the OP is having, it makes it very easy to diagnose a noisy circ or verify that they are all operating.
If you want a switch, by all means put one in.
"If you can't explain it simply, you don't understand it well enough"
I remember some older pump had on/ off rocker switches on them, maybe early Armstrongs?
I'd like a switch and small led indicator light on ALL circulators.
On some jobs I put a cord with a plug so the pumps could be easily connected to a generator during power outages, wood boiler installs mainly.
I have 6 pumps connected to a solar controller in my shop and they all have plugs, with receptacles wired to the relay box outputs. Mainly so I can keep trying various pump brands and styles.
The ECM have displays so no light needed, but a switch that required a screwdriver to operate might be nice.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
Any motor driven appliance must have a disconnect switch installed within 50' of the motor and in site of the motor. That's code. The fact that most hot water boilers have a single switch for the boiler and the circulators is fine.
Thermostats don't count as disconnects. Disconnecting wires is not a disconnect.
A cord with a plug can serve as a disconnect.
If multiple switches are installed for serviceability that's fine-1
Thanks for all the great info. I never expected to get so much in such a short period of time.
- I, too, would like to know why my circulators are failing. Any ideas how I could find out?
- My system has no leaks, but I don't know if it's using a lot of make-up water.
- My system has an electronic control module with LEDs that show when each circulator is running, which is handy.
- My thermostats can be used to partially control the pumps, but they can't shut the pumps off entirely. And in the winter, even at their lowest setting, they will at times call for the pumps to run. I'm looking for something to electrically disconnect the pumps.
- One of the zones on my burner feeds a hot water tank. In fact, it's the circulator for this zone that died yesterday. It would be a little more difficult for my wife to control the temp setting on this zone than for a zone controlled by a normal thermostat.
- A plug and receptacle setup for each pump would be acceptable.
- I disconnected the wires only as a temporary workaround. I would not consider it for a real solution.
* I'll most likely go with a 20a single pole switch on each pump as my final solution. *
Again, thank you all very much for sharing your knowledge and opinions. I really do appreciate it.
I see 2 major causes of failure in wet rotor circs.
The biggest is water quality. Systems with slow undetected leaks continually refill with oxygenated makeup water. This causes corrosion and chemistry issues that are really tough on circulators. Often you can see this by just looking at the water in a clear container. Checking the PH and TDS levels in the water is a bit more scientific. If you turn off the fill valve, does the system hold pressure?
Circulators which are incorrectly sized will also fail prematurely. What is the model and application?"If you can't explain it simply, you don't understand it well enough"
Gosh, properly selected and installed wet rotor circulators should last 15- 20 years. Plenty of them out there have, I see them and pictures of vintage circulators all the time.
Stop and start is hard on any motor also. Sized so it runs mid curve, or varies speed to match the the load. Constant circulation, or as close as you can get, in addition to what Carl suggested.Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
My 4 current circulators are Grundfos model 15-58FC. I don't know how to characterize the application other than to say 3 are used for gas-fired indoor hot water heating zones and one to power a hot water tank fed by my Buderus boiler.
My original heating system was installed 50 years ago and had the big (6" diam. by 12" long) old style circulators. I had to have a number of those replaced in the 40 years I used the system.
My new system was installed about 10 years ago and I have already installed two new pumps since then. And now I need a third. None have been replaced more than once.
Maybe the problem is the water. For some years I used a glycol/water mixture in the system, but I think it's all water now.
My water district's annual water quality report:
https://www.chelmsfordwater.com/sites/chelmsfordwater/files/uploads/ccr2016.pdf doesn't even use the term TDS, so I've asked them why.
I see that Grundfos now offers the Alpha2 line of circulators, which feature a so-called "AUTOADAPT mode, will automatically analyze the heating system, find the optimum setting, continue to adjust its operation to changes in demand." This seems like it would handle a problem of a pump being incorrectly sized for the system.
Anyone have any experience with this line of circulators.
Thanks again, everyone.
There is also an Alpha 1 circulator that may be a better choice, a less expensive version without the AutoAdapt. If the zones do not have multiple zone valves or thermostatic valves on radiators, no need to use the AutoAdapt function.
I'd run a good hydronic cleaner through the system, check the TDS, and buy RO or deionized water to fill with if the water is excessively hard or high TDS. Old glycol can leave a sticky mess behind.
Most hardware or plumbing stores have water hardness test kits, that tells part of the story, the amount of scaling minerals present.
TDS looks at the conductivity of the water the hardness plus any other minerals or deposits in the water.
You should be able to find a local water treatment company to test your water. Local universities, well drillers air an Ag extension can usually test.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0
I had a hot water system where they had used glycol and it became diluted and contaminated. We lost pumps on that job in a few months and then installed a filter. It was a combination black pipe and copper.
sounds like the same thing. Magnetic particles0
Be sure to get your water quality under control before adding ECM circs like the Alpha. ECM's are more susceptible to damage from poor quality water than conventional ones."If you can't explain it simply, you don't understand it well enough"
It would be nice to think so. 'tain't true. They will auto adapt, within a remarkably broad range -- but not indefinitely in either direction. Nothing would. With them -- or anything like them -- it is a very good idea indeed to try to come as close to the correct size as you can to begin with, and then let them fine tune.Geezer said:
I see that Grundfos now offers the Alpha2 line of circulators, which feature a so-called "AUTOADAPT mode, will automatically analyze the heating system, find the optimum setting, continue to adjust its operation to changes in demand." This seems like it would handle a problem of a pump being incorrectly sized for the system. ...
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0
Still getting very good responses, for which I'm very appreciative.
How does an ordinary heating system guy coming to the house know how to set a circulator pump like my Grundfos? It has HI, MED, and LO switch settings. Do they automatically set them to HI and let 'er rip. Or do they kind of look at how much baseboard is involved in each zone and make a judgement? I've never noticed any of them sizing up the situation. They never leave the basement.
My original question of installing switches to control the pumps has enlarged into a question of if/how I can get longer life out of the pumps. That may not be answered in the short term, but I'm thankful for all the insight you've all provided.
getting the circulators to last longer I would say 90% of the time is related to water quality.
If your heat emmiters are baseboard, CI radiators etc. (not a radiant system) standard temp drop through the system is 20 degrees. So measure the supply and return water temp from each zone and subtract....should get 20 deg if moving the correct gpm with a load on the system. Try to stay within 5 deg either way....so 15-25 deg0
Thanks, EBEBRATT-Ed. I'll try measuring temp drop. Does that indicate what speed that the circs should be set to?
I'm also checking with heating company tomorrow re: water quality.
Yes. If your TD is to high you need a higher speed on the pump. Too low a TD you need a slower speed0
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