Intermatic 156T4042A heater control (fireman's) switch kitIntermatic Heater Control (Fireman's) Switch Kit, 156T4042A In stock$4699
Intermatic 156T4042A heater control (fireman's) switch kit
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Intermatic Heater Control (Fireman's) Switch Kit, 156T4042A

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$4699
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Quick overview

  • Coordinates heater and pump Ties the heater to the filter pump so the two never run out of step.
  • 20 minute lead Turns a gas fired pool or spa heater off about 20 minutes before the filter pump shuts down.
  • Stops pounding and knocking Circulating the residual heat out of the exchanger prevents the banging caused by overheated water sitting in the heater.
  • Reduces scale Less scale and lime deposit forms when the heater is not left full of hot static water.
  • Extends heater life The heat exchanger is the expensive part, and a fireman switch is the cheapest protection for it.
  • Kit form Supplied as a kit for fitting to an Intermatic time clock.
Full description and specifications ↓

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Product details

The Intermatic 156T4042A is a heater control kit, the part most people call a fireman's switch. It coordinates a gas fired pool or spa heater with the filter pump so the heater is always shut down first.

How it works

The switch turns the heater off roughly 20 minutes before the filter pump stops. During those minutes the pump keeps water moving through the heat exchanger and carries the leftover heat away.

What that prevents

When a heater shuts off at the same moment as the pump, the water trapped in the exchanger keeps absorbing heat with nowhere to go. That is what causes the pounding and knocking owners hear at the pad, and it drives scale and lime deposits onto the exchanger surfaces. Running the pump on for a while afterwards avoids both and adds years to the heater.

Fitting

It is supplied as a kit for installation with an Intermatic time clock controlling the filter pump.

Specifications
Brand Intermatic
Manufacturer part number 156T4042A
UPC 078275701137
Type Heater control (fireman's) switch kit
Function Turns the heater off approximately 20 minutes before the filter pump
Used with Gas fired pool and spa heaters on an Intermatic time clock
Shipping weight 3.35 lb
Ships Parcel

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Questions and answers

What people ask about this product, answered by our pool techs.

What is a fireman's switch?
It is a small switch fitted to the time clock that shuts the heater down ahead of the filter pump, so the pump keeps circulating while the heat exchanger cools.
How much lead time does it give?
About 20 minutes. That is enough run time to carry the residual heat out of the heater before flow stops.
Why does it matter?
Water left sitting in a hot exchanger pounds and knocks, lays down scale and lime, and shortens the life of the heater. Cooling it down under flow avoids all three.
What does it work with?
It is built for gas fired pool and spa heaters running alongside a filter pump on an Intermatic time clock.
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