# Fireman Switch W/Intermatic Timer



## BBQ (Nov 16, 2010)

What is a fireman switch? :blink:


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## donselec (May 7, 2011)

is this a listed package?? the ones i have done the heater has a built in flow switch...no flow no heat...


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## A Little Short (Nov 11, 2010)

BBQ said:


> What is a fireman switch? :blink:


It is just a micro switch that mounts at the dial for a timer. The timer trips the micro switch a certain amount of time before the timer turns off the pump or whatever load.
It is used, in this instance, to turn a pool heater off 20 mins before the pump turns off so water will continue to flow across the heat exchanger after the heater is off.


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## A Little Short (Nov 11, 2010)

donselec said:


> is this a listed package?? the ones i have done the heater has a built in flow switch...no flow no heat...


The heater hasn't arrived so I don't have the specs yet.
But no, the timer, fireman switch, and heater aren't a packaged unit.


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## bmailman20 (Jan 4, 2013)

The firemans switch closes when the timeclock turns "on". Then the switch open 20 mins before it is set to turn "off". This prevents the heater from running with the motor off. There is a cam on the on/off switch that engages the F/M switch.


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## bmailman20 (Jan 4, 2013)

I also should have noted that the FM switch breaks the low-voltage connection on the heater.


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## B4T (Feb 10, 2009)

The idea is to circulate cold water through the heater to cool it down..

Otherwise the burner could start melting the solder inside the unit...


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## A Little Short (Nov 11, 2010)

donselec said:


> is this a listed package?? the ones i have done the heater has a built in flow switch...no flow no heat...





Little-Lectric said:


> The heater hasn't arrived so I don't have the specs yet.
> But no, the timer, fireman switch, and heater aren't a packaged unit.


Got the pool guy to give me the model of the heater. it is a Pentair Mastertemp 250 NA.

So I looked up the specs here to see if they helped. It appears that it has a pressure switch and not a flow switch, but one could be added.

There are terminals for connection to the fireman switch so I should be able to wire it ok.

One thing I did notice was the unit can heat either the pool or spa and now I wonder if I should get a second fireman switch for the spa side of the timer should I decide to feed it with two different 20A circuits. 
But to be honest, I don't know enough about the pool/spa plumbing to know if two switches would be needed.

The pool and spa each have their own motor, but I'm thinking the pool pump would be running and is for the filter, which would filter both the pool and spa? And the spa motor is for recirculating and the jets.
So probably the pool pump would be on all the time, with the exception of when the timer is off?


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## bmailman20 (Jan 4, 2013)

Yes, you'll need 2 FM switches, paralleled in the timeclock enclosure, and then run to the heater. 
Sometimes I'll use 18/2, but other times I'll use thwn so I can run it in the carflex with the heater feed. 
Good luck!


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## A Little Short (Nov 11, 2010)

bmailman20 said:


> Yes, you'll need 2 FM switches, paralleled in the timeclock enclosure, and then run to the heater.
> Sometimes I'll use 18/2, but other times I'll use thwn so I can run it in the carflex with the heater feed.
> Good luck!



Did you mean to connect them in serial instead of parallel? I called Intermatic and they said to wire them in series. They said the switches couldn't be wired in parallel.

If in serial, if the switch, for say the pool pump, happened to be open then the circuit couldn't complete. Neither switch would the allow the heater to come on if one was open. Doesn't make sense to me what Intermatic said unless both timers were set the same.

If they can be in parallel, is this how you would do it:
wire one from first switch tied to wire one from 2nd switch
wire two from first switch tied to wire two from 2nd switch
then a tail off of each to the heater?


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## irocin350 (Mar 2, 2011)

Little-Lectric said:


> Did you mean to connect them in serial instead of parallel? I called Intermatic and they said to wire them in series. They said the switches couldn't be wired in parallel.
> 
> If in serial, if the switch, for say the pool pump, happened to be open then the circuit couldn't complete. Neither switch would the allow the heater to come on if one was open. Doesn't make sense to me what Intermatic said unless both timers were set the same.
> 
> ...


There is no need for a second fm switch , I have wired dozens if pentair heaters and the vs pumps in side the heater is the fireman switch jumper , the spa button is if ur heating only a spa and using a inteli system ,yes u are correct those heaters don't have a flow sensor they have a adjustable pressure sensor , as for the spa pump are u sure its not an air pump ??


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## irocin350 (Mar 2, 2011)

Ps u don't normally put the spa part of the on a time clock , I usually put a switch to control that spa motor


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## irocin350 (Mar 2, 2011)

That way the home owner can put spa on at anytime


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## A Little Short (Nov 11, 2010)

irocin350 said:


> There is no need for a second fm switch , I have wired dozens if pentair heaters and the vs pumps in side the heater is the fireman switch jumper , the spa button is if ur heating only a spa and using a inteli system ,yes u are correct those heaters don't have a flow sensor they have a adjustable pressure sensor , as for the spa pump are u sure its not an air pump ??


It is a regular pool/spa/hot tub motor 9.7A 230V



irocin350 said:


> Ps u don't normally put the spa part of the on a time clock , I usually put a switch to control that spa motor


The home owners want the spa on a timer so when they are away from home the spa will circulate and the water won't stagnate.

They also want a switch for the pool pump, in conjunction with the timer, so they can turn it off if they just want to use the spa.

With this info, do you still say a second FS is not needed?


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## irocin350 (Mar 2, 2011)

Little-Lectric said:


> It is a regular pool/spa/hot tub motor 9.7A 230V
> 
> The home owners want the spa on a timer so when they are away from home the spa will circulate and the water won't stagnate.
> 
> ...


Assuming g that the spa is part of the pool meaning it overflows in to the pool on weather or not to fm the spa , usually from what I have seen is that the spa has an air pump or the spa has a circulation loop in it that the piping don't go back to filter that it just takes water from pool and kicks it out the jets in the spa area if this were the case I would not put a fm on the spa IMO i would in use a fm on the filter pump and not the spa ,I would let the heater heat the pool " haha ita a pool heater not a hot tub " as for the switched pool pump b carful so that when they shut the switch for the filter off that the heater shuts down aswell, just by killing power at the filter don't mean the heater is off


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## A Little Short (Nov 11, 2010)

irocin350 said:


> Assuming g that the spa is part of the pool meaning it overflows in to the pool on weather or not to fm the spa , usually from what I have seen is that the spa has an air pump or the spa has a circulation loop in it that the piping don't go back to filter that it just takes water from pool and kicks it out the jets in the spa area if this were the case I would not put a fm on the spa IMO i would in use a fm on the filter pump and not the spa ,I would let the heater heat the pool " haha ita a pool heater not a hot tub " as for the switched pool pump b carful so that when they shut the switch for the filter off that the heater shuts down aswell, just by killing power at the filter don't mean the heater is off


The spa is separate from the pool and does not flow into it. I think they will have a diverter in the plumbing so they can use just the spa, and I suppose to just heat the spa should they want to.

That's why they won't to have the spa on a timer, to run it while they're gone (they leave a lot) so the water isn't green when they get back.

I really don't understand this set up with the plumbing.:no:


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## irocin350 (Mar 2, 2011)

Little-Lectric said:


> The spa is separate from the pool and does not flow into it. I think they will have a diverter in the plumbing so they can use just the spa, and I suppose to just heat the spa should they want to.
> 
> That's why they won't to have the spa on a timer, to run it while they're gone (they leave a lot) so the water isn't green when they get back.
> 
> I really don't understand this set up with the plumbing.:no:


Ok I guess once u confirm that the piping for the spa goes threw the heater , then u would need 2 fm switches in parallel , and I would let them just use the manual switch on the t/c to shut the pool filter off and vise versa fit the spa . Just don't forget all ur bonding


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## dronai (Apr 11, 2011)

I wired up a Pentair with an automated controller for the pool pumps heater lights etc. There was a jumper I had to remove that was the "firemans switch" I had to bypass that and run it thru my timer in my control panel. Sounds like you need to loop thru your timer then back.


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## A Little Short (Nov 11, 2010)

irocin350 said:


> Ok I guess once u confirm that the piping for the spa goes threw the heater , then u would need 2 fm switches in parallel , and I would let them just use the manual switch on the t/c to shut the pool filter off and vise versa fit the spa . Just don't forget all ur bonding


To wire the switches in parallel, you would take lead one from pool switch and tie it to lead one from spa switch, then pigtail off with a single lead.
Do the same with lead two for each switch.
Is that correct?



dronai said:


> I wired up a Pentair with an automated controller for the pool pumps heater lights etc. There was a jumper I had to remove that was the "firemans switch" I had to bypass that and run it thru my timer in my control panel. Sounds like you need to loop thru your timer then back.


Yep, the heater has two terminals labled "fireman's switch" that have a jumper between them. You have to remove the jumper and put the leads from the FS one to each terminal.
I will probably put the low voltage leads in same conduit as the load conductors.


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