5000W Heater Not Blowing Hot

[IanMurphy]

Hey guys, new here so apologies if this isn't the best place to post this. I just got an Oulette 5000W garage heater (model number OAS5000) for really cheap because the guy said the thermostat switch wasn't working. I just got it home to start troubleshooting and the t'stat appears to be working fine, so I am looking for help troubleshooting this thing. See attached photos including the wiring diagram.

The unit blows warm, but definitely not hot. If I unplug the fan motor, the heating coil gets red hot, but when the fan is plugged in in cools right down. The resistance across the heating coil was ~13 ohms so I think its working fine. There is a 150*F thermal cutoff switch that is working as it should. There is also a 110*F fan delay switch which is not working - the switch is always closed causing the fan to always run regardless of the temperature.

1) Could this fan delay switch be causing the lack of heat? I'm wondering if the fan should be turning off when the temperature drops below 110*F to give the heating coil a chance to warm up. When its running on max, it should be pretty hot to stand in front of right? Should be coil be red hot? Any help on troubleshooting this thing is greatly appreciated.

Thanks!

 

[mike93lx]

The fan on my 5500 watt heater never shuts off and it puts out a ton of heat.

Do you have a clamp on meter? I wonder what it is drawing

 

[IanMurphy]

The fan on my 5500 watt heater never shuts off and it puts out a ton of heat.

Do you have a clamp on meter? I wonder what it is drawing

I do not have clamp meter unfortunately. Theoretically it should be drawing ~20amps at the max setting. If I can get my hands on a clamp meter I will post an update

 

[American Locomotive]

These 240v electric heaters with moderately powerful fans do not blow particularly hot air, it's just their nature. The reality is 5kw is not a lot of heating power. That's only ~17,000 BTU/hr. Your average small torpedo heater is like 50-60,000 BTU/hr, and a typical home furnace will be 80-120k BTU/hr.

The absolute temperature of the heating element doesn't matter, ~5kw of heat will still blow into the room. The fan temperature switch is purely a "comfort" thing, so the fan won't blow ice cold air when you first turn it on.

13 ohms @ 240v is ~18A, which works out to 4.5KW. Close enough to 5KW. Granted resistance goes down as the element heats up, so you could double check with a clamp meter while in operation - but I'm reasonably certain the heater is working within design parameters. Remember what I said earlier, the temperature of the air doesn't particularly matter. 5KW of heat will still go into the space.

 

[Showkey]

Not sure this applies to your heater but:

Typical heater temperature rise is 30-60*F. So 50* in might be 90* air out with would feel warm not hot.

 

[IanMurphy]

These 240v electric heaters with moderately powerful fans do not blow particularly hot air, it's just their nature. The reality is 5kw is not a lot of heating power. That's only ~17,000 BTU/hr. Your average small torpedo heater is like 50-60,000 BTU/hr, and a typical home furnace will be 80-120k BTU/hr.

The absolute temperature of the heating element doesn't matter, ~5kw of heat will still blow into the room. The fan temperature switch is purely a "comfort" thing, so the fan won't blow ice cold air when you first turn it on.

13 ohms @ 240v is ~18A, which works out to 4.5KW. Close enough to 5KW. Granted resistance goes down as the element heats up, so you could double check with a clamp meter while in operation - but I'm reasonably certain the heater is working within design parameters. Remember what I said earlier, the temperature of the air doesn't particularly matter. 5KW of heat will still go into the space.

It is possible its working fine, but I'd be really unimpressed. I am talking about putting my hand inches away and its only sort of warm, not standing across the room. I do have a 34,000 BTU propane heater for comparison and that thing blows really really hot and can heat my uninsulated garage up in an hour.

I feel like the coil should be red hot even when the fan is blowing air across it, no?

 

[American Locomotive]

No, the coil should not be red hot. Most electric air-over electric heaters do not have the elements glowing. Infrared? Sure, but not air-over heaters.

A 34,000 BTU propane heater is twice as powerful, so it will feel much hotter. Like I said, most 5KW class heaters with a moderately powerful fan will only feel warm, especially if the space is cold (like 30-50 degrees). It's only 17,000 BTU/hr. Your resistance measurements check out, but you could verify with a clamp meter. If you see ~20A while running, the heater is performing as designed.

 

[IanMurphy]

No, the coil should not be red hot. Most electric air-over electric heaters do not have the elements glowing. Infrared? Sure, but not air-over heaters.

A 34,000 BTU propane heater is twice as powerful, so it will feel much hotter. Like I said, most 5KW class heaters with a moderately powerful fan will only feel warm, especially if the space is cold (like 30-50 degrees). It's only 17,000 BTU/hr. Your resistance measurements check out, but you could verify with a clamp meter. If you see ~20A while running, the heater is performing as designed.

Thanks for the info. I am still not convinced. We have a 1500W space heater that feels hotter than this thing. I think I am going to buy another used 4800W heater just to compare, then sell one of them.

 

[American Locomotive]

Thanks for the info. I am still not convinced. We have a 1500W space heater that feels hotter than this thing. I think I am going to buy another used 4800W heater just to compare, then sell one of them.

Once again, the temperature of the air coming out is completely irrelevant. It's a combination of air flow AND temperature that matters.

1500W space heaters usually have very tiny fans that move small amounts of air. Therefore the air they generate is going to be extremely hot. But it's very little hot air. Most 240v 5kw class heaters choose to have much more powerful fans that move a lot of air. The result is far more warm air, vs. a little hot air. By your logic, my 1,000 watt hot-air-gun should be able to heat my entire house since it glows orange and can set things on fire with its air stream. But it doesn't.

Here's a simple test. Turn the heater on and it get warm, unplug the heater and quickly check the resistance across the plug with the heater's switch still on. If you still get around ~12-13 ohms with the heater hot, it's working just fine.

 

[u3b3rg33k]

your heater is fine. running it with the fan disconnected was stupid. stop doing that. also, look at the distribution of the heating element vs the fan area. you're going to get a ton of unheated air blowing out one side of it and hotter air out the other.

 

[PoorUB]

If you buy anything, buy a volt meter with an amp clamp and see how many amps it is drawing. The element should be drawing just over 20 amps.
Like others have said these electric heaters don't feel that hot while running. If the element is drawing 20 amps it is working fine.

 

[yeldogt]

The way to check the unit is to use it inside a heated space ...

At 50 degrees ---- the temp rise depending on the fan will not feel that high. Agree on not operating the unit w/o the fan running ..... you will overheat the element. It's clearly getting hot

 

[IanMurphy]

Once again, the temperature of the air coming out is completely irrelevant. It's a combination of air flow AND temperature that matters.

1500W space heaters usually have very tiny fans that move small amounts of air. Therefore the air they generate is going to be extremely hot. But it's very little hot air. Most 240v 5kw class heaters choose to have much more powerful fans that move a lot of air. The result is far more warm air, vs. a little hot air. By your logic, my 1,000 watt hot-air-gun should be able to heat my entire house since it glows orange and can set things on fire with its air stream. But it doesn't.

Here's a simple test. Turn the heater on and it get warm, unplug the heater and quickly check the resistance across the plug with the heater's switch still on. If you still get around ~12-13 ohms with the heater hot, it's working just fine.

Okay that makes sense, thanks for the advice

 

[BillK]

Ill just add my 2 cents I also have 5000 watt heater in my garage and the air is certainly not what you would consider hot. More like luke warm but it does the trick and heats the garage just fine.

 

[kberjian]

A little more to expand on the theory is that BTU is calculated by the change in temperature of intake air to outgoing air (Delta T) x the volume of air being affected. A heater like the one you describe needs to have the same air pass through it numerous times to get it warmed to the desired temperature.

If you have a well sealed space with no drafts you would be better suited to a heater that has a higher air moving and a lower Delta T which is typically more efficient.

If you have a less sealed/poorly insulated space you would be better served to have a heater that has a high Delta T and a lower air moving volume.

Both heaters have the same BTU output but both will not produce the same results.

 

[Showkey]

Both heaters have the same BTU output but both will not produce the same results.

BTU’s are BTU’s so end result is the same …….the time to the end result is the variable.

 

[u3b3rg33k]

yeah if you're in a super drafty garage, all a heat gun is gonna do is slag whatever you point it at. the building will still be cold. radiant heat is the answer here, imho. if you're going electric, then there's no efficiency to forfeit, whereas condensing gas vs radiant gas = big efficiency hit.

 

[PoorUB]

Both heaters have the same BTU output but both will not produce the same results.

I disagree. Two 5KW electric heaters, one that moves 2x times the air as the other will feel different, but you will get the same BTU out of both. The higher CFM fan will feel much cooler than the other and have a lower delta T but other than air throw they will produce the same BTU and heat pretty much the same. If both heating cols are consuming 5KW. So if they are not producing the same BTU, where is it it going?

 

[kberjian]

If you have a room that is a 30F and you want to get it to 60F so you can paint something.

The heater that has a delta T of 15F you will need to recirculate that same air 2+ times to get any air to the target temperature which is why it works well in a sealed room. In a drafty room the air will be vented/cooled before it gets recirculated back into the heater. You will never get air that meets your target of 60F.

If a heater has a delta T of 40F the output air meets your target temp in the first pass, so if you are in the path of the heater it will at least be getting some air at the target temp. Regardless of the efficiency of the room you can get your target piece to the right temperature.

 

[PoorUB]

Ummm, no! Try again!

The 15 degree delta T will heat the 30 degree air to 45 and as the room heats up the delta T stays pretty much the same so at some point the return air is 60 and the 15 delta T brings up the supply air to 75. BTU is BTU.

 

[u3b3rg33k]

If you have a room that is a 30F and you want to get it to 60F so you can paint something.

The heater that has a delta T of 15F you will need to recirculate that same air 2+ times to get any air to the target temperature which is why it works well in a sealed room. In a drafty room the air will be vented/cooled before it gets recirculated back into the heater. You will never get air that meets your target of 60F.

If a heater has a delta T of 40F the output air meets your target temp in the first pass, so if you are in the path of the heater it will at least be getting some air at the target temp. Regardless of the efficiency of the room you can get your target piece to the right temperature.

for how far in front of the heater before the air gets cold? are we setting the heater up against the work while we spray flammable VOCs at it?

 

[American Locomotive]

Both heaters will take the exact same amount of time to heat the space. Heaters that blow less but hotter air might "feel" warmer if you are directly in front of the heater, but it will take more time for that heat to disperse around the space. Heaters that blow more, but cooler air, will not "feel" quite as warm directly in front of the heater, but the space will heat up more evenly.

But all said and done, 5KW is 5KW. Both heaters will eventually heat the same space up to the same temperature in the same amount of time. They'll just "feel" different during the warm-up phase depending on where you have the heater aimed, and where you are standing in the space.

 

[like2wheel]

Ill just add my 2 cents I also have 5000 watt heater in my garage and the air is certainly not what you would consider hot. More like luke warm but it does the trick and heats the garage just fine.

Same here @ 5600 watts.

 

[nadogail]

i too have 5KW heaters, they warm the area in front of the heaters and raise the spirits of those standing in the air stream; but they are still small heaters.

 

[IanMurphy]

You guys were right, the heater is working normally. Its drawing close to 21 amps actually and it does heat up the space in a couple hours. Thanks for all the replies