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  • Writer's pictureAllison Hale

Ice on my heat pump

AHHH! Why is there ice on my heat pump? Yesterday the weather was 34* and raining and we answered no less than 15 calls from customers concerned about ice accumulation on their Heat Pump (or outdoor unit/condenser/air conditioner). Today the temperature is 37*, the rain has mostly stopped, but the calls keep rolling in! What's going on? And what can the homeowner do to resolve the issue? Keep reading to find out. Do you have a heat pump? Maybe! In Central Texas, heat pumps are used for homes that are all electric (no gas!), and homes with duel-fuel heating systems (most likely if your home has propane as its gas source).

Whats going on here? We could do a whole blog post on what a heat pump is and how it works, and the refrigeration cycle, but in simple terms: A heat pump, in heating, is removing heat from the outside air and transfering that heat inside to warm the home. In cooling- it works exactly the opposite. Moving heat from inside the home, to the outside air. Ever noticed how in the summer the air around your outside unit is VERY warm? That's the heat from inside being dispersed outside. Same thing now in heating- that outside unit and coil is getting COLD because it is removing the heat from the outside air and therefore becomes VERY COLD. Cold enough that precipitation (uh hum... rain) will freeze on it! What do to about it? Let the Heat Pump do its job! A heat pump, running in heating, naturally runs a defrost cycle periodically according to its controls. Basic units run defrost cycles based on time alone, smarter units use sensors and algorithms to run defrost at the perfect times (also called on demand). What happens when a Heat Pump Defrosts? When a heat pump runs a defrost cycle, the usual course of events are- the fan stops running, the coil heats up, and the ice melts! This can look CRAZY if you don't know what's going on. This can look like steam or smoke, but it's really just melting or sublimation of ice! Ok, But there is a LOT of ice.... One thing that can happen is if there is a lot of water falling off the roof, and there is no rain diverter or gutter above the condenser, is ice accumulation of the cabinet away from the coil. This can cause ice accumulation to hit the blade, build up on the top of the unit, and build up to the point where it can't keep up by defrosting. Options: 1. Switch your system to Emergency Heat to keep your home warm without using the heat pump. Find the area of your thermostat that switches between heating and cool and look for "EM", "EM HEAT", or "EMERGENCY HEAT". Can't find it? Try googling your thermostat and 'emergency heat' or give us a call- we can usually walk you through it on the phone. 2. Have a roofer install a rain diverter above the unit to keep excess water from pouring onto the unit. Need a recommendation? Give us a call- we know a few good roofers! Ok, but there is a LOT LOT LOT of ice.... 3. If you are concerned- call a professional! We are always here to help. SOS Mechanical 512-238-6699 There is a possibility that something is wrong. Defrost boards go out, reversing valves, stick, dirty condensers impede heat exchange, etc. We can get a technician out to your home to diagnose the issue and propose possible fixes! Just give us a call!

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