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Thread: Heater on timer?

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    krcossin's Avatar
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    Heater on timer?

    So I am working with my electrician and a question came up about the heater. I have a commercial duty timer that connects to the circuit breaker box which is to control my pump. He asked if the heater needs to be on the same timer, or is the heater to be plugged in, temperature controlled at the unit and it will cycle on/off based on water flow? I wouldn't want the heater to be on with the pump off. Advice is appreciated.
    2007 - 24' AG Doughboy Desert Spring dished 1.5', with DB Power Pak II-1hp pump, DB Sequel I Plus DE, Hayward H-Series Heater 100k + 8gal LQ.

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    I cant say exactly about your heater but mine has to have flow or it will shut down it would be a good guess that all heaters have a flow control to shut them down with no flow. so yes your pump would have to run to keep the heater from turning off, if your heater runs with the pool pump off it would not have a flow switch. I would find it hard to beleave that a heater would not have a flow switch of some kind. hope this helps
    Ric W
    My Pool
    8605 gal fiberglass, 3/4 hp pump, sand filter, aquabot cleaner, heat siphon heat pump, tiger river(sumatran) spa

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    You would want you heater to be on a separate power source not tied to the pump if I am understanding you correctly. Example if your pump cycles off the heater would stop heating water due to no flow but some heaters still have a cool down cycle where you would want power to the heater to still be running. Not sure if that made sense or not...

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    krcossin's Avatar
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    I confirmed the heater has a flow sensor, so I will just plug it in and let it do it's job. Then unplug it during inactive months.
    I agree a dedicated circuit is required for the pump. I was just considering having the heater be on a timer that was in sync with the pump, but it doesn't sound like that necessary.
    2007 - 24' AG Doughboy Desert Spring dished 1.5', with DB Power Pak II-1hp pump, DB Sequel I Plus DE, Hayward H-Series Heater 100k + 8gal LQ.

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    As far as I know you are supposed to shut the heater down 20 minutes prior to your pump cycling off. So long as your timers are correlated accordingly you should be fine. Perhaps I am wrong in the 20 minute prior deal but that is what a neighbor told me.

    Could be a myth, I keep forgetting to ask the pool builder when I stop by the shop.
    62,800 Litre IG Vinyl
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    Clearwater/Zodiac LM2-24S SWG
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    250K NG Heater

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    mas985's Avatar
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    If your heater is like mine, both Haywards, the exhaust fan will come on if there is no flow through the heater. This occurs when the heater has power to it and does not depend on if the flame is on or not. I think it is a safty precaution.

    I did wire my heater with my pump but I have a full controller which has a heater cool off mode so the controller will extend the run time of the pump 15 min to make sure the heater has cooled off. I did it this way so the exhaust fan will not run when the pump is off and the Hayward tech recommended this for my situation.

    You may be able to wire the heater separately to a different timer but make sure the on time is less than than the pump run time or the exhaust fan may kick in.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Kr, what you want to have the elsectrician do is install the "fireman's switch", which turns off the heater 20 min before the pump shuts down. As was mentioned, this allows the heater to cool down - it's not a good idea for that hot water to just sit in the plumbing. The heater manual should have instructions for wiring up the fireman's switch and the timer's manual should tell how to attach it to the timer (If they happen to be Sta-Rite Max-E-Therm heater and Intermatic timer, I can tell you how to do it)
    Good luck with it, if I can be of further assistance, just ask
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

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    yep, a fireman's switch is what mine has. i use an intermatic timer that controls my pump on and off time..a panel is slaved to the intermatic that has these circuits in it and a small control panel dial that i can adjust for how long i want the pump to run after the timer switches off, which turns off the heater first. you can get various lengths..mine is 14 minutes. and yes, you can melt pvc pipes easily..been there done that. came in my pool shed and found water spraying out of a few pieces of pipe that had bent to ****. i had manually turned off the heater..and the pump, at the same time versus my usual "wait 15 minutes. some pool heater companies will say that the nipples provided with most heaters (schedule 80 pvc) will keep the pipes from melting but given they are only about a foot long and my pipe melted 3 ft away, i'm not buying it
    • 15K IG gunite/plaster pool • Pentair: Whisperflo EE 1 HP • Nautilus FNS + 48 DE Filter • IntelliChlor IC40 •
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    JasonLion's Avatar
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    Not all heaters require a fireman's switch. Mine says that hooking it up directly to the pump timer is fine. I believe that it depends on how much residual heat there is in the transfer coil once the heater goes off. If there is too much thermal mass in the transfer coil area then the water will get too hot when the flow stops, but not all heaters have that issue.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    yeah, mine says hooking it up directly is fine as well in the manual, but dependent totally on the pvc 80 nipples apparently being long enough that any residual heat will dissipate before it hits the pvc 40. like i say, having been there and spent 150 bucks and a day to replace most of my shed piping, i like the security of the switch. some heaters come with a switch built in or you can purchase an optional switch kit. given i was getting a bunch of electrical done anyways, it was easy enough and cheap enough to get an external box with the electronics needed built to do the job for me. it also switches my swg off in advance as well..doesn't appear that's necessary but, what the heck..it didn't cost me anymore to have it wired that way.
    • 15K IG gunite/plaster pool • Pentair: Whisperflo EE 1 HP • Nautilus FNS + 48 DE Filter • IntelliChlor IC40 •
    • Spectrum Amerlite SAm • Admiral S20 Skimmer - Circular Weir • Kreepy Krauly •

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