Question about Mr. Heater MHU45LP

2 Answers

Heater will not ignite

Hi I have a MHU45LP and it worked fine. But now it will not ignite I changed the igniter, flame sensor and even swaped the board out. The gas comes on and still no heat unless I lite it myself. Gives 2 flashes which means no flame detected, and I already know that. Q: How much volts should I have at the igniters?
Any help in this matter would surely save my hairline.

Posted by on

  • 2 more comments 
  • Anonymous Mar 10, 2008

    I have identical issue. I have troubleshot it back to the board as well. I ordered on online today as I have not yet located my original invoice (unit is 8 months old). I will pursue reimbursement for board.

  • Anonymous Mar 18, 2008

    same exact problem.

  • Pnatrick Apr 11, 2008

    same problem but i have the 75 unit

  • shaun35 Dec 06, 2008

    did changing the board work mine is doing the same thing and they are sending me a board



2 Answers

Thanks, I called the manufacurer and they told me it was most likely the board which was not igniting flame. They are sending me a new one. I will see if that does the trick. Thanks for your help.

Posted on Mar 04, 2008

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that hasĀ over 10 points.


    An expert whose answer gotĀ voted for 2 times.

  • Contributor
  • 30 Answers

The igniter should have 120v if it is Hot Surface Igniter (HSI). You may be having a problem with gas pressures. Possible transformer problem also if you changed that with other parts.

Posted on Mar 04, 2008


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

MHU45LP wont ignite all 3 burners

blocked orifices at the two burners or weak pressure from valve.Are you running nat. gas or propane?

Sep 18, 2014 | Mr. Heater MHU45LP

1 Answer

I have a Big Maxx MHU45LP....1 1/2 yrs old....used maybe 5 times. 10 hrs running time at most...... The furnace was hard starting right from installation.....the burner was hard to ignite.....try 3...

There are several things that could be causing this problem. Low gas pressure comes to mind, first. Followed by an electronic ignition problem. Which may simply be caused by poor line voltage or a dirty sensor. Amazingly, not using the heater regularly, can do more harm than good. Because, in the long down times, spiders like to go into these heaters and build nests. These nests can really clog things u

As far as the lots of flame on ignition, this is probably a result of delayed ignition, which causes a gas build up.

In addition, if you live in an area that is more than 2000 feet above sea level, the pressure regulator should be adjusted to provide more gas.

Juts in case you have misplaced your Owners Manual, I have included a link to it, that you can download and print for future reference.

If you continue to have problems and are dissatisfied, contact ENRICO (the manufacturer of Mr Heater Products), Technical Service Dept at 800-251-0001

Hope this has helped you troubleshoot the problem and hopefully solve the problem.

Apr 18, 2011 | Mr. Heater Natural Gas Garage Heater -...

1 Answer

My mhu45lp mr heater ceiling mount won't start. the green light is blinking steady and exhaust fan is running but burners will not ignite.I did jump the brown and red wires on the pressure switch which did...

Check the electrode is clean and sparking , clean flame sensor and check connections are tight . check hi and low limit switch . check pilot is not blocked .

Jun 24, 2017 | Mr. Heater MHU45LP

1 Answer

My mhu 75 worked just fine until the regulator on the tank froze. Got the gas to flow, combustion air blower came on but no igniters. Control board LED is blinking the fast flash saying everything is fine....

check the flames sencor is clean and the igniter check connections to the board on both wires , check hoses to pressure switch are not cracked or , you could cut off abit off the end to get better connection on the tubes hope this helps

Jan 14, 2011 | Mr. Heater MHU45LP

1 Answer

I have a 2 year old rheem power vent water heater model # 42vp50fw. It suddenly stopped working. It will try to ignite. The igniter will glow and the call for gas will ignite the burner. After a few...


The flame sensor is bad....and it is not sensing that the flame has lit....

Some models have a separate flame sensor and some use the ignitor to sense the flame...

If it has a separate sensor then clean it with a soft cloth... if it is the ignitor then the ignitor is bad...


Nov 25, 2010 | Rheem 50 Gallon FVR NATGAS Water Heater...

1 Answer

My gas dryer starts fine than the flame goes out

replace the coils. i promise you. and here is a guide to most gas dryer problems that even a kid can see.

starts fine, cycles off, igniter comes on, hear a click, and no flame.-coils.
(can also be intermintent)

igniter stays on, no flame.-flame sensor

no glow from igniter.-igniter

remember, always allow about one minute for ignition.

Oct 06, 2009 | Frigidaire GLGR331A Gas Dryer

1 Answer

Gas heater won't work

Which flame sensor did he replace? The pilot flame or the plenum temp. sensor.

Dec 14, 2008 | Carrier 38CKC036 Air Conditioner

3 Answers

My goodman gmt090-4 shuts off about 10 sec. after burners ignite

Check the pressure sensor. I tapped on mine a few times, removed the hose and checked it for blockage and replaced. It has been working fine since. I do have a new sensor on order.

Oct 04, 2008 | Goodman GMS90703BXA Heater

Not finding what you are looking for?
Mr. Heater MHU45LP Logo

Related Topics:

837 people viewed this question

Ask a Question

Usually answered in minutes!

Top Mr. Heater Heating & Cooling Experts

Paul Carew

Level 3 Expert

3328 Answers

Mack Baxter

Level 3 Expert

383 Answers

vance jones

Level 2 Expert

120 Answers

Are you a Mr. Heater Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides