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Amana HTM Plus Water Heating System

JEMJEM Member Posts: 7
Any Wallies here familar with these units ? It appears to be a gas furnace / water heater that has a seperate 40 gallon hot water holding tank with a thermostat on the tank it's self. 95K btu rating, 90% effiecent, direct pcv venting. Any known problems or are they any good at all ? Thanks for any help. Joe


  • I remember those

    I was an installer in the 80s, and we sold those units. I even had one in my own house.

    The HTM (heat transfer module) was originally designed to be a cooling heat exchanger in Raytheon radar systems.

    The glycol got thick with age, and the open system expansion tank would boil over and make a mess of everything within the cabinet.

    I'm a little more careful now, about being on the bleeding edge of technology. Someone else can buy the brand newest designs, first.

    Even though the early bird gets the worm, it's the SECOND mouse that gets the cheese.

    (Steven Wright)

  • DaleDale Member Posts: 1,317

    If there are a few still running I would be amazed. Amana had a great name brand until these things. They went through many many recalls and field fixes, the furnace at least. The DHW tank was plastic lined and seemed to outlast the furnace every time. The tank was the first modern looking domestic hot water storage tank fed off of what was really a tiny little boiler, the HTM. The thing had 2 flat heat exchangers, one for the condensing one for the latent heat transfer. Thinking of something nice to say the schematic was very well done and fun to train techs on since it had so many lines. My favorite was the water valve that flushed the heat exchanger and usually shut off. I knew of one house that had this ( the non condensing version) in the back yard with pipes running inside. Sort of the first outdoor boiler. After the first dealer wouldn't look at it in the winter the address was quickly known to all companies who advertised "we service all brands" and who then made exceptions.
  • TomTom Member Posts: 265

    These units were a nightmare to keep running. We installed the condensing furnace as well as the outdoor "boiler" that would heat the domestic hot water and a hot water coil in an air handler.

    Amana finally started offering replacement 90% furnaces that did not have the HTM module. We, as well as Amana, lost a chunk of money on those units. I would really be shocked to see some still running.

  • TomTom Member Posts: 265

    These units were a nightmare to keep running. We installed the condensing furnace as well as the outdoor "boiler" that would heat the domestic hot water and a hot water coil in an air handler.

    Amana finally started offering replacement 90% furnaces that did not have the HTM module. We, as well as Amana, lost a chunk of money on those units. I would really be shocked to see some still running.

  • RangerRanger Member Posts: 210
    I have..

    ...a friend of mine that is replaceing two outdoor units as I type this.He called Amana and thay have very few parts left available.There were alot of those I used to run into (or wanted to run into) in Ocean County,New Jersey.And as actor
    John Larroquette's character,Capt. Stillman in the movie "Stripes" would say..."Have that removed!!!"
  • joeljoel Member Posts: 931
    the mouse

    HAHAHAHAHAHA I read that 3 times before i got it, (should i admit that ?) that's a good one!!!!!!!!!!

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • rich pickeringrich pickering Member Posts: 277

    My father HAD the outdoor unit. -40, 2am and snowing was not a good time to learn how to service them.
  • FrankFrank Member Posts: 1
    Yes I still have a working Amana HTM

    I know it's hard to believe, but I still have a working unit that is now 19 years old and is used to heat my house and hot water in NJ. The Amana MTM system was used by the builder for the whole subdivision. By now I'm sure most were replaced (I managed to get one for spare parts). The early units were a big problem especially with cracking in the HTM heat exchanger. Amana solved that design problem and redesigned the glycol pump housing that would crack after a few years. The control circuit boards did not allow for any extra current draw. After replacing 2 control boards over 4 years, I added a switching relay that solved the current draw problem. One really has to be sure that the HTM heat exchanger is sealed to the recuperator otherwise you will have a CO leak. Aside form ignitor changes, my last major repair was to replace the diverter valve for the hot water tank 9 years ago. This is one of those appliances that you need to keep an eye on to find problems early. I guess that I'm fortunate in knowing how to do my own repairs.
  • S EbelsS Ebels Member Posts: 2,322

    Tell me you're NOT considering buying a house or something with one of these in it!!!! The local Amana dealer, good people, nearly went bankrupt over these dogpiles.
  • Ken D.Ken D. Member Posts: 820

    We installed many of the HTM units in the 80's. I know of at least one that is still around in a hardware store I frequent, although I have not had to work on one for years. The leaking of glycol from the pumps and subsequent corrosion was a chronic problem. Our wholesaler did try to work with us, but things snowballed to fast. The HTM, like the Blueray was an idea that looked good on paper, but the reality did not agree.
  • enb54enb54 Member Posts: 2
    2010 and Going Strong

    There are a lot of stories about awful experiences with the HTM, but we are starting to hear a litany of similar difficulties regarding the "new" condensing boilers, which of course is what the Amana HTM was, only it arrived in 1980. The technology was far too advanced for the time, and manufacturer training was unfortunately not up to the task, while many heating outfits didn't understand the need for following installation instructions nearly to the letter. The modern versions are experiencing similar problems, and likely have similar solutions, usually regarding electrical bonding and heat exchanger/combustion chamber cleaning, semi-annual inspections, etc. These devices are not the good old low maintenance boilers of yesteryear (neither was the HTM) and require a maintenance schedule by a trained individual who understands the technology and has the test equipment required (combustion gas analyzer, clamp-on ammeter, digital voltmeter, manometer, etc.). Religious maintenance has kept my HTM going for nearly 30 years now, and I do not expect to have to replace it in my remaining lifetime. I have researched the modern replacement boilers, and they are all far more sophisticated than the HTM, which means they all also require even more maintenance. Most HTM problems were installation/maintenance related, and I would suspect that this will also be the case with the modern condensing boiler systems. 

    Since 1982 this HTM has performed very well, and basic maintenance consists of cleaning the furnace filter, oiling the blower motor (indoor), changing the glycol every 4 or 5 years, and ensuring there are no leaking hose clamps. The climate here (Edmonton, AB) usually hits -30C (-22F) in January and the outdoor unit hasn't complained yet, have replaced the ignitor 4 times in nearly 30 years and rebuilt the circulating pump (not the motor) twice. Some basic understanding of how your sophisticated heating appliance works, plus regular maintenance will keep your device running for a long, long time.

    I just had to respond when I saw one poster ask if any of these HTM's still existed. Always remember that installation and maintenance is everything when it comes to reliability and longevity, so if someone comes to install your fancy new boiler and does not have the required experience and test equipment (and uses it!), then prepare yourself for many future difficulties...
  • HTMGuyHTMGuy Member Posts: 2
    Need HTM upper heat exchanger

    I also still have a working Amana HTM furnace with water heater. I totally agree that it was well before its time but still a good furnace. After 25 years I now need the upper heat exchanger. I can still buy a new one but am looking for a "parts HTM " if any one has one for sale.


    HTM Guy
  • HTMGuyHTMGuy Member Posts: 2
    Need HTM upper heat exchanger

    I also still have a working Amana HTM furnace with water heater. I totally agree that it was well before its time but still a good furnace. After 25 years I now need the upper heat exchanger. I can still buy a new one but am looking for a "parts HTM " if any one has one for sale.


    HTM Guy
  • Tim McElwainTim McElwain Member Posts: 3,893
    If memory serves me they hooked

    up a fresh water feed to those units that flushed thew condensate after each call for heat. It seemed like a god idea at the time.

    Interesting I was on board a couple of destroyers that used a Heat Transfer Module concept to cool the drive unit on radars from Ratheon.

    When I worked for the gas company we sold a bunch of those here in RI. Almost everyone of them had some kind of problem or another. I do however have a friend of mine who still has one and he has stocked his own spare parts. He takes very good care of it so it has lasted over 25 years.
  • J3CubJ3Cub Member Posts: 1
    Cheers to Amana believers

    I ran across this website while looking for ignitor gaskets.  It’s a great forum (though not easy to find the link to the Amana threads), and I see there are others out there who feel the way I do about the Amana HTM outdoor system, but I’m disappointed in the negative comments, so I thought I would add my bit.  I've had my Amana HTM outdoor unit since I built my house in 1982, and if I built again I would look for the same system!!  Yes it had problems, but they could all be fixed.  I don’t think there is any system out there that could beat it, especially for the price.  And there are after market sources for all of the components now.

    And by the way, the Amana outdoor HTM is NOT a boiler system.  It heats a fluid solution of water and antifreeze, which is then run through a heat exchanger to transfer the heat to the space or material to be heated.  Basically the same as in an automobile.  Very simple, effective, and efficient.

    I initially put in 2 indoor air handlers and the 40(U.S.) gal. hot water tank for my 2 storey house which involved 2 diverter valves, but about 3 years later I added a third indoor handler with a 3rd diverter valve for the (attached) garage that I had since added.  That was a challenge, because the dealer got electrical and plumbing schematics (supposedly from the area distributor) for the layout, but there was no way it could work that way.  The dealer just said it was electrical and just left me with the problem (literally – he just packed up his truck and left) and sent me a bill.  I had some help from an electrical engineer family member and we figured out how to get it to work.  As it turned out, their plumbing schematic wasn’t right either.  But we redid it and got it to work and it’s been great.  I have since redesigned it so that the fluid never has to go through more than 2 diverter valves.

    When I added the garage, I had a local welding shop make me a mount for the outdoor unit so that it hangs on the garage wall, rather than sitting on a pad on the ground.  I had brought my plans to him, but when I went to pick it up, it was quite different, and I’m glad because it is simpler, plenty strong and looks neat.

    The system design certainly had weak points, but between Amana’s and the component manufacturer’s and my improvements it’s been pretty trouble free for many years although I just had to replace the ignitor a few days ago, but that’s a pretty easy job both to troubleshoot and to replace, and any other system is prone to the same kind of problem.  I always keep a spare ignitor on hand because I live in the country, and even if I lived in the city, it could fail on a weekend.  I like to have several ignitor gaskets on hand, and I just found out that they are made of a fibreglass material (pure white) which I can apparently get locally at a gasket material supplier, although I’ve never had a problem getting precut gaskets such as at Goodman.

    I initially found a dealer that was willing to sell me the system for me to install (including fully charging it with fluid), and then he came out to check out the work and fire it up.  No problem there, but I live in a rural subdivision with a community water well and reservoir system that used to occasionally run low in summer and would shut down.  My house is the second highest in the community, and that happened the first summer, and my hot water tank got drained by other’s opening their taps or flushing their toilets while there was no water pressure, such that they were getting their water from my tank by means of gravity, and that collapsed my tank’s plastic liner, causing it to crack and leak.  The dealer replaced the tank under warranty, but I found out it’s an Amptrol tank, so it’s essentially not an Amana fault, and it’s used in many other systems.  I solved that problem by putting a check valve in my house water supply line.  I think they later included that in the installation instructions.

    However, in having the dealer replace the tank, I found out how glad I was that I had installed the system myself.  Their workmanship stank, and I had to redo their plumbing work.  I have since realized that many of the problems that others had were also due to shoddy workmanship, and a “get it done and leave” frame of mind.  I understand that a heating contractor can not stay in business providing hours of labour without a return.  But that should have been solvable with a higher price, because the concept is sure worth it.  I know of 2 different local plumbing contractors who have this system in their own places, and won’t trade it for anything.  My neighbour’s house is quite similar in style and size, and their heating bill is atrocious with standard furnaces and hot water tanks, compared to mine.  He is an engineer in the gas business and he didn’t believe at first that I could even heat my house with this system “when it’s -40 and the wind is blowin”.  The workmanship of the dealer that I bought my 3rd tank from was not any better.  I since found a reliable and very qualified contractor who also was willing to work with me and let me do much of the work, and I always paid him for his time even when he was essentially training me, and I bought my parts through him, but he has since retired.  Fortunately, there doesn’t seem to be anything that I can’t fix on my own now.  It is a very basic electrical and mechanical system.

    Probably the #1 problem was the hoses.  The fluid charging instructions have you pinching off the hoses in the HTM at various stages.  That’s a dumb way to treat any hose, and these hoses were plain rubber with no reinforcement and no other layers of material.  After having a couple of hoses go on me (at the worst times), I replaced them with copper sweat tubes and elbow assemblies with 1” inline ball valves (I had to cut them a bit shorter to make them fit), so the only hose material in my HTM cabinet now is the short lengths necessary to connect these assemblies to the HTM and to the pump, leaving only about 1/8” at each connection to develop any leak, and I use only good quality reinforced automotive heater hose material, so it’s pretty trouble free now.  Two of the valves are in the fluid return line from the indoor units with one between the reservoir line tee and the charging tee, while the other is between the charging tee and the pump.  These 2 valves had to be opposite each other in direction and rotated into different positions so that they can both be operated without interference with the other or anything else.  The third valve is between the pump and the HTM itself.  I also put a small ball valve in the reservoir line to eliminate that clamp as well.  These are all the places that the hose clamps were required but this is a lot easier to manage.

    Early on I made up a charging pail with a fitting on the side at the bottom to attach a valve and the plastic hose to run to the charging tee.  But I have since soldered a 45 elbow and a ¾” ball valve to the charging tee, and then I leave the length of clear plastic tubing attached to it, with a plastic plug in the end to keep it clean, and I just curl it up over the reservoir.  I think I’ll even put a hole with a fitting in the side of the reservoir near the bottom and attach the plastic line from the charging tee to it, so that the charging tee is permanently connected between the charging tee and the reservoir, instead of to a pail.  That way I can eliminate the charging bucket setup.

    I also made up a toggle switch with a set of stiff insulated wires with alligator clips on the ends.  That way it conveniently clips onto the screws on the terminal board on the outside of the electrical box, and allows full control of the pump motor where I can see what the fluid level is doing in the reservoir during charging.  I think I’ll mount it permanently onto the pump motor base, or maybe onto the outside of the electrical box.

    For purging air from the top of the HTM during charging, I also made up a fitting and elbow assembly with a valve, with a length of plastic tubing that goes into the cabinet above the reservoir and down into the reservoir.  It’s easy to install and remove with a crowfoot wrench.  I haven’t bothered screwing down the flue cap for many years.  It has never even budged, and we get a lot of wind.  And I gave up on the seal under the flue cap – it was a joke.  I used to faithfully paint the cabinet top to keep it from getting rusty, but for years now I just let the cabinet top get rusty.  Someday maybe I’ll see about getting it powder coated, but I have no idea whether it would be any better.   

    To facilitate draining the system, I installed a tee with a drain cock at the lowest point in the system, and I installed a purge valve at the highest point in the indoor plumbing to facilitate purging air out of the system.

    In less than 10 years my HTM developed a crack around the bottom just inside the recessed area where the ignitor and ground wire are located.  I kept having to replace my ground wire due to it burning off, till my reliable contractor said that there shouldn’t be that much heat there.  After a while I was doing some extensive work including replacing the cabinet top which means that you have to take the HTM out, and when I was cleaning it for painting with some high heat paint, I could see that it was cracked.  They replaced it under warranty, but I had the contractor come out and check everything after I had replaced it, and he determined that the fluid was returning too cool, resulting in condensation in the bottom of the combustion area, and recommended that I put in the 120,000 BTU orifice plate (I had been using the 100,000 plate).  He also changed the combustion blower fan with a new one that Amana had upgraded with more blades for better air supply because it wasn’t producing the right amount of negative pressure (as measured with a manometer).  So I don’t really know exactly why the HTM cracked, or if it was just my luck that it cracked, but that was before 1991, and I haven’t had a problem since, although I acquired a used one from him as a spare just in case.  20 years isn’t bad.

    My hot water tank went again a few years ago because someone drained some water from the tank with the water shut off, but didn’t open up a tap to let air in.  So the liner collapsed and cracked allowing water to get outside of the plastic liner.  It didn’t take long for the tank to develop a rusted pin hole on the top.  They’re expensive tanks, even if you could get it wholesale, and you still have the same potential problem.  I debated getting a stainless steel tank made up where I would just use the guts of my tank, but I couldn’t find anyone willing to make me one without an engineer’s stamp.  The hot water recovery was so good that we pretty much never ran out of hot water, even if we washed the car with hot water in the winter, so I figured we didn’t need a tank at all.  I installed a copper tube heat exchange assembly (with dual wall tubing) that I set up using the pressure and thermal relief valve and the thermistor from the tank.  It worked fine for several years, but then it developed a water (not heating system) leak that I figure was due to thermal shock fatigue as the cold water (our water supply is very cold) contacted the hot pipe inside.  It was also a little undersized (despite assurance from its manufacturer) and didn’t give us enough hot water for some applications, so I am replacing it with two in parallel and made up my own preheater tubing (also double walled) in series, that I can replace myself if thermal shock causes it to fatigue.  Another benefit of designing it this way is that it provides no restriction to heating system fluid flow, whereas the Amana/Amptrol tank is quite restrictive causing more strain on the pump.

    I had the pump/fan motor bearings start to squeal several years ago, but I was able to get some oil drops into them every few months at first, and then I finally took it off and replaced the bearings (readily available for $7.00 a pair at a local industrial bearing supplier).  And it’s been going great ever since.  If I hear them start to squeal again, I’ll know to replace the bearings right away if it’s still reasonably warm weather, or if it’s already wintery, I’ll be able to wait until after winter is over.

    The gas valve has never been an issue.

    A few years ago I recall having to bypass the solution temperature limit switch (the vapour pressure control that has a probe inserted up into the core and runs to the electrical box by means of a capillary tube), and it was in the summer, rather than when it’s colder anyway.  Everything else seemed to be fine from gas valve to combustion blower, to flame cone.  What I noticed with a mirror and flashlight was that the HTM core itself was getting quite choked up, and there was a lot of residue both in the inner area, and in the outer portion of the core inside the stainless steel jacket.  So I figured I may as well remove it and take it to a radiator shop.  He put it into a bath and flushed it all out both through the fins and inside the fluid passages, and pressure tested it for leaks.  When I put it back into operation, everything was working like new, so I guess that was the problem, and it’s logical when you think it through.  In the summer heat, it was getting too hot, with the exhaust gases not being able to pass adequately through the fins and out the flue cap.

    The original diverter valves were Honeywell, but if the valve motor or secondary switch caused problems you had to remove the whole operating component as one from the brass body, which meant that you had to drain the fluid first (and go through the recharging again afterwards).  The guys that installed my third indoor air handler threw them all out (I needed 3) and replaced them with “Superior” valves which they said were a much better valve.  Well they were anything but.  The rubber piece on the valve arm actually disintegrated in the antifreeze causing other problems, and it didn’t take long.  I ended up taking them all out and putting Honeywell valves back in, but Honeywell had improved their design by that time by permitting the electrical head assembly to be removed without opening up the valve.  But even at that, I haven’t had any trouble since anyway.  Also getting the valves from the dealer who got them from Amana who had to get them from Amana in the U.S. who got them from Honeywell, meant that the cost to me was $300.  I went directly to Honeywell locally who had no problem selling them to me for $85.00, although it took a while for them to order them in.

    Another problem that Amana had was that the fluid would hammer in the pipes when a diverter valve would actuate, just like household plumbing pipes do sometimes when somebody closes a tap.  Their fix for this was to not solder the valves to the pipes, but connect them with rubber hoses.  That worked to eliminate the hammering, but then you have hoses that can leak.  I still have that and have changed the hoses connections a couple of times.  But the next time I have the system down for maintenance, I intend to resolder them and instead provide some tees with vertical air “chambers” for hammer cushioning.

    I have switched to aluminum compatible automotive antifreeze since Amana stopped supplying theirs, and it works fine.  I haven’t changed it yet, but will probably do that this summer or fall.  I also have a slight pump leak to fix.

    The original pumps were poor and leaked readily, and I also had a housing that cracked.  But they replaced it with a more rugged pump and I’ve had next to no problems.  I got a new pump from the local Goodman branch.  I hear that some guys are repairing the pumps.  I wouldn’t know what there is to repair other than change the seal, so if they are changing the seal, I’d sure like to know where to get the new seal and how to change it.

    The indoor air handlers are common to other systems, but other than having to replace a couple of the coils due to leakage, they have been fine.  Goodman also supplies the coils.

    As for working on it outside in the winter time, I open up the cabinet and check the fluid level in early fall and give the hose clamps a little tweak, oil the indoor air handler motor bearings, and it’s pretty much trouble free in the winter, in fact all year for the last several years.  I made a flat laying catch tray out of an antifreeze jug with a cutout just big enough to fit under the pump, to catch pump seal drips, and empty it in spring and in fall and then filter that with a coffee filter and pour it back into the reservoir.  If the system should cause me trouble when it’s miserable outside I depend on alternate heat until it’s not so bad outside.  If it’s sunny out and not blustery it’s not so bad even if it’s cold.  I have used electrical heaters in the house when necessary, but plan to install a gas fireplace in the basement just to have for normal enjoyment reasons, and that should provide enough emergency backup to keep the house from getting too cold.  With the fireplace, I intend to also install a stainless steel tube assembly above the flame area that I can open up to the water system for alternate hot water.  I have thought of setting up a second HTM as a backup also, if I can find one.

    If anyone knows of a system being removed, I’d be interested in obtaining at least the outdoor unit.

    Cheers to the Amana HTM believers.

  • enb54enb54 Member Posts: 2
    Amana HTM pump parts

    The HTM uses a version of the Gorman-Rupp 149 Series, there is a repair kit which you can Google (see attachment), so just find a GRI Pump distributor, and have them look it up, good luck!
  • sanfordsanford Member Posts: 2
    old plumber

    hi guys i have 2 amana tanks a freind would like to install one in his house i lost the nut and adapter of the top of the tank.would any one have one or be able to tell me where i could get one .? george at 403 358 6911
  • sanfordsanford Member Posts: 2
    old plumber

    hi guys i have 2 amana tanks a freind would like to install one in his house i lost the nut and adapter of the top of the tank.would any one have one or be able to tell me where i could get one .? george at 403 358 6911
  • RuggedEngineeringRuggedEngineering Member Posts: 1
    Used HTM Parts available

    I recently removed my Amana HTM furnace with 24 years of service. The boiler and heat exchangers are still in good shape. It is a self-contained furnace model with either 80,000 or 100,000 BTU input (selectable with an air inlet baffle change). I also have the hot water holding tank. The exhaust sheetmetal area had started to leak, and the pump/blower combination has deteriorated as well and is noisy. It was still functioning when I removed it, but felt that the approach to replacement would be best served by removing it before failure at a much worse time of year for replacement. I won't keep it around for too long - please respond with any interest in parts from the unit.

  • htmbill721htmbill721 Member Posts: 2
    pump motor

    if anybody has a good used 110 volt pump motor i need to buy one, it must be in good working order, not concerned about the pump just a good motor
  • htmbill721htmbill721 Member Posts: 2
    pump motor

    if anybody has a good used 110 volt pump motor i need to buy one, it must be in good working order, not concerned about the pump just a good motor
  • jwagjwag Member Posts: 1
    Amana HTM outside unit Model ERGW0012

    Unit is in excellent working condition.  Available.  Price negotiable.  Became  surplus in remodeled home now using two furnaces instgead.  It heated comfortably a 400 SF house (California).  Motor and pump were recently replaced and like new.
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