Picture of the Honeywell 5-2 Thermostat RLV310A, Mounted and Operating.

Honeywell Line Voltage Digital Thermostat RLV310A Review




We purchased two of these Honeywell line voltage digital thermostat RLV310A  units for the electric baseboard heaters around our home.



At a cost of about $30 from Lowe’s home improvement center, the price seemed okay.  Indeed, the RLV310A has proven highly reliable and trouble-free.  It’s an excellent electric heating thermostat (t-stat).

Honeywell line voltage digital thermostat RLV310A. Picture of the Honeywell 5-2 thermostat RLV310A, mounted and runing.
Honeywell line voltage digital thermostat RLV310A. Honeywell 5-2 thermostat RLV310A, mounted and running.

The RLV310A is lots quieter. That is, it makes no clicking sounds as it turns the heaters on and off.  How so?  Well, it uses an all-electronic switch (a triac) to switch on and off our 220v heaters.  Plus, its computerized control system and precise temperature (temp) sensor make a tight temp swing.  Now assume that we have right sized heaters in well insulated rooms.  Then, these temp swings will stay within a few tenths of a degree of the set temp with this t-stat.

Below sums up our work with this modern day manual yet digital t-stat.



Benefits, Features, Advantages, and Pros of the Honeywell Line Voltage Digital Thermostat RLV310A 

Easy to Install

Honeywell’s supplied installation guide was easy to follow and quite straight forward.

Installation took under a half hour and needed only a Philips screwdriver since we were just replacing an existing t-stat, instead of installing a new one from scratch.

Warning: This 220v thermostat controls the line voltage supply to the heater.  So if power to the circuit is not shut off, the installer could receive a severe high voltage shock.  This is not a 24-volt model. So treat it with respect. Observe, to-the-tee, all warnings, cautions, and installation tips as laid out in the users guide.

Just Two Line Voltage Connections

The RLV310A has just two black wires. It’s a single pole switching t-stat, that you hook up as you would a regular light switch.  It hooks into just one side of the electric heater supply line.

This t-stat has no ground lug, as this t-stat comes in an all-plastic case.  The mounting plate is also plastic, and thus, non conductive. The two-wires-only approach further eases installation.

Easy to Set Non Programmable Thermostat

Since this digital t-stat is not programmable, the users guide is thus, simple and brief.  Though digital, this is strictly a manual thermostat.

With just two buttons (to raise and lower the room temperature), the RLV310A is quite easy to work.  It’s temperature readout is digital; not a dial.

Fast Response

It responds right away when you change the temp set point. That is, this t-stat instantly turns on the heater full blast when you raise the temperature.  And, it  turns the heater off when you lower the temperature.

Tight and Precise Temperature Control

In terms of comfort, we liked the tight temp control of this unit. It allows no more than a plus or minus 0.35 degree of swing, before flipping the heater on or off.  Now this means that the heaters cycle more often than with the bi-metal t-stats we’d used prior.  But with other noises around, we didn’t hear this cycling, not one bit.  Why?   Because the triac based switching here is totally quiet — no clicks.

Lowers Energy Costs

Now this t-stat limits the size of the temp swings.  Indeed, the user’s guide says that due to this tighter control, heating bill saving should be a good bit. Lower heat costs are a real concern when paying for baseboard heating. Why?  Because each room costs a few dollars per day to keep warm as it is.  So, there is quite a bit of savings likely, when your electric heating covers several rooms.  While we realized moderate energy savings, comfort in the rooms indeed improved a lot.  No doubt, we reduced our savings because we set the room temp higher.

Never Sticks ON or OFF

It never sticks in either ON or OFF state.  The reason we replaced the mechanical temperature sensors with this one, was the sticking.  Those cheaper t-stats would stick ON now and then. Then, the room temp would skyrocket to 85 degrees in almost no time.  This happened due to the micro switches binding up with the bi-metal sensor strip. But the RLV310a uses a non moving sensor to read room temp.  It also has a computer to interpret the readings and then electronically switch the heaters.  So it never sticks.  Not that we’ve seen.  No metal contacts to bind up.




Disadvantages, Cons, and Problems of The Honeywell Line Voltage Digital Thermostat RLV310A

Non Programmable Thermostat

This automatic t-stat is not at all programmable. But a span adjustment between the ON and OFF temps, the temperature differential would be useful.  See next item for more details.

Non Adjustable Temperature Differential

It offers a very narrow yet non settable temperature span of approximately 0.7 degrees total. That is, when the room temp falls 0.35 degrees below the set point, this t-stat turns the heater on. Then, when the temperature rises to 0.35 degrees above the set point, this thermostat turns the heater off. Thus, the heater comes on and off several times per minute.  This can startle and distract when all else in the room is quiet.  But as we said, with quiet baseboard heaters, you don’t even notice this switching.

Cycles Heaters A LOT Each Hour — Not Adjustable

Our heaters hum, ping, and clank each time they switch off and on. Indeed,  we may have stopped the clicking from the old mechanical t-stats with this one.  But we have also raised the noise problem from the heaters. Beware of this if you upgrade to a digital thermostat. This t-stat would likely work best with those almost silent hydronic electric heaters.

Buttons Make No Noise When Pressed

As is true with so many devices today, no sound comes when you press the UP and DOWN temp buttons.  This silence can complicate use by the blind and vision impaired. But since these controls are the only two to work, no sound seems no big deal.

Non Lit Display

The temperature display does not light up.  So you cannot view it without turning on a light in the room.

Our Rating of the Honeywell Line Voltage Digital Thermostat RLV310A  

Overall, though it’s non programmable, this electronic thermostat worked quite well for us. This t-stat works just as stated in the users guide.  So we rate this Honeywell line voltage digital thermostat RLV310A at 93 out of 100.  This t-stat brings the precision of digital devices to the easily worked manual line voltage thermostat market.

Where to Buy the Honeywell Line Voltage Digital Thermostat RLV310A

You can find this product at Lowe’s, Home Depot, and other home improvement and electronics centers.



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References

Revision History

  • 2017-03-11: Originally published.