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Hydrotherm Hydropulse

Greg SwobGreg Swob Member Posts: 167
Worked on the first one of these I've seen. No manual and whomever installed it placed screws for rear panel to the wall making it tought o get at. At least I could get to the electrical panel and one of the press. switches if they need serviced. Looks more like a central vacuum power unit than a boiler- tall and cylindrical. It makes a popping sound somewhat like a Pulse furnace, hence the name, I assume.

The problem was simple enough, gurgling sounds suggested to me the burner chamber was full of condensate. Found cond. drain blocked, cleaned out cond. port of boiler, fired up and all OK, except for a sticking zone valve.

Now, has anyone had experience with these units? Someone wrote 3-5-84 on a side plate, I assume this was install date and a co-worker said the home is around 20 yrs. old. Are they still made and are parts available? Fuel is LPG. Any helpful suggestions for general preventive service on this unit? Meanwhile, I will contact a Hydrotherm dealer to see if a book is available to help me figure the inner workings of this thing.

I have several concerns with this particular boiler. One, the combustion air intake is open to the atmospehre with no turn down or screen & exhaust leans from boiler, causing condensate to drip onto walkway. There may be small leak(s), but without completely removing the jacketing, could not tell for certain. Also, I would love to repipe this baby with P/S, pumping away; add a proper air eliminator, outdoor reset & relocate it so a guy can work on all components, etc. Thanks- Greg


  • mp1969mp1969 Member Posts: 226
    Remember these well

    The "Hydro-Pulse" was the unit that was put on the market in the early 80's in response to the energy crunch back then. Most of the R&D was done in the field. I changed out more than my share of cracked heat chambers and baby sat many of these through cold northern WIsconsin nights. They were very difficult to service and very tempermental. I was a certified installer and tech but really could not afford to sell these! (Too many callbacks)
    I believe they are still made and have cleaned up there reputation and ease of servicing.Hydo-Therm is a good company and were just a little too anxious to get this product on the market.
    I still have scars on my hands from removing the bolts and spark plug that made up the mixing chamber for combustion.
    I had excellent luck with Hydo-Therm's conventional boilers and modular set-ups. I would be curious to know how many of the 80's vintage Hydo-Pulses are still in service.
    Also you might want to check into parts availability before you open one of these up!

    Have fun!

  • Greg SwobGreg Swob Member Posts: 167
    Hydrotherm website

    Thanks for your response. I did go to Hydrotherm website and found they still make them or at least 3 versions of them. Two look the same as the central vacuum cleaner-shaped one I saw yesterday! I thought I'd go to the experts first for advice on service. I bet they are hard to work on and this one is smacked against a wall where several access panel screws are about unreachable.
    There was a lot of corrosion to the base, but it looked like the radiator hose, I mean 'optional vibration isolation flex connection' had leaked at the boiler return port sometime ago. This probably caused the external corrosion. I think I will find a dealer who handles Hydrotherm and get more specifics on parts, etc.

    At least I got it running, told them I'd do some research and go back next week for more intensive study of the system once I was armed with more info. Greg
  • Mark EathertonMark Eatherton Member Posts: 2,542

    These puppies are notorious for failing in the combustion chamber and leaking condensate at the base. An idea well before its time, the units were built with cast iron which is not a good material for acidic condensate.

    As soon as I got certified to work on these puppies, I decided I couldn't afford to install them either. Too many moving parts, and too many problems.

    In addition to the rotaing sequencer, theres the reed valves that open and close 60 times per second, and then theres the combusion fan, and the ignition transformer.

    In deference to the manufacturer, I'd HOPE that they have changed some things in the look a like version, but from what I've seen, they're still going down the path of the V2 buzz bomb jet pulse combustion technology.

    BTW, they're not supposed to pop as you said in your first thread. Sounds like failing reed valves. Besides all that, they sound like a bull moose in rut season with nasal congestion when they're running.

    Look for an alternative.

  • Ken D.Ken D. Member Posts: 820

    We installed and serviced a fair amount of them since the early 80's. Have'nt installed one in at least 10 years, but there are still some out there new and old we have serviced. Customer complaints ran from too noisy to too tempermental. Many leaking heat exchangers, problems with the venting, condensate, you name it. The trouble shooting was always an adventure and factory tech support was nil (although it may be better as they are now ownwd by Mestek who is a much better company). They are very efficient and it would be nice if they could be engineered to be more dependable.Lennox made a pulse furnace to about 5 years ago. They were dependable, but problems with heat exchangers led to their discontinuation. It seems that any technology that utilizes higher flame temps. don't seem to last. (Pulse, Blueray,etc.)With energy as expensive as it is today, the out of the box thinking is needed, but R&D is essential to dependability.
  • Boiler GuyBoiler Guy Member Posts: 585

    I installed at least 30 of these units. While I agree they were somewhat tempermental in the early years, I was actually able to obtain reasonable service life out of them. The problems I found most common were heat exchanger failures due to the serpentine tubes rubbing from normal expansion/contraction.
    The manufacturer made numerous revisions to the control system, the first of which was to get rid of the original timer. I still have about 5 running with that original timer though. The customer missed the deadline to have them retrofitted and now does not want to spend the money. That said, after about '84 the exchanger design was modified too which substantially improved the longevity. The oldest one I have is 22 years - TOTALLY original. I just replaced a pressure switch this past winter. Two sets of diaphrams and 2 spark plugs in 20 years is pretty good service life IMHO.
    Lack of product support in the early '90's forced me to look at alternatives. The weak CDN dollar pretty much killed the product after that.
    I still have lots of parts and information though if anyone is interested.
  • Greg SwobGreg Swob Member Posts: 167

    This forum has never failed me in the 6 years I've been visiting and observing here! I'll share your comments with the owners. Recently purchased the home-nice young couple with babies, literally. The 'pop' sound reminded me of the Lennox pulse units. It does indeed sound unusual when it runs. Can't share Mark's comparison as there are only deer, antelope and cattle around here to compare with!

    There was a small pile of misc. parts boxes in the mechanical room left over from the previous guys who worked on it. These were all used and I assume taken from the unit, then simply left there. Is that like leaving a service log? Just leave the changed out parts so some future service person can see what the history has been? Kind of like an archeological dig finding some old parts (that most probably still work fine).

    Time to put on the salesman hat and convince them do what I said in my earlier post- revise, repipe, replace. Next, a heat loss calc, then look at offering some options. Thanks- Greg
  • bill clintonbill clinton Member Posts: 111

    Installed several of these decades ago. If you're going to mess with the innards of this beast, open up the top and check the construction. The earlier models had the combustion chamber bolted up to the top with a silicon rubber gasket for a seal. The combustion chamber was bolted in before the pressure vessel cannister was welded up. THAT GASKET CANNOT BE REPLACED! If you start torqueing around on a rusted in spark plug, you may just put enough stess on the thing to start a leak. You might want to warn the customer beforehand and disclaim responsibility for that kind of problem.


  • Greg SwobGreg Swob Member Posts: 167
    I may need to take you up on

    the parts issue. Maybe you can help me squeeze another year out of this one and I can help you get rid of some odd parts if we end up needing any. I found out a local plumbing contractor sold these years ago and likely installed this one. I want to go back next week and do a more thorough review and follow up on this machine and check it over for leaks better. Now that I'm armed with some helpful advice and can download a manual for the modern pulse units from Hydrotherm's site- I feel a little more comfortable about working on it. It was like looking under the hood of a foreign car trying to figure what the heck was all supposed to be happening there. I still don't feel completely comfortable over what is all hidden inside and hopefully there will be no need to find out! We did at least find an electrical schematic in their boiler room. It has an Amtrol indirect for DHW also. I do need to do something about the combustion air intake if nothing else. Greg
  • bob elmorebob elmore Member Posts: 41

    there is a good stocking rep in central illinois.
    comfort sales 217-656-1655. they stock parts and boilers.
    honest and knowlegable people.
  • hrhr Member Posts: 6,106

    with another brand gets to be a challange with that 2" vent :)

    I know a company that replaces HPs with Munchkins and Y's the 2- 2" into a 3" for the Munchkin connection. They remove dual HPs and replace with one Munchkin. You do take a hit in the output, however. You need to check with HTP for this venting modification.

    A large HVAC shop in my area sells tons of H-pulses. Lines em up like soliders and pipes them to hydro air units scattered around the building. Mostly churches and commercial work.

    The "Champion" spark plug always made me chuckle :)

    hot rod

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  • mp1969mp1969 Member Posts: 226
    Is it warm yet?

  • mp1969mp1969 Member Posts: 226
    Is it warm yet?

    Personally I would wait for warmer weather in case this unit turns into a can of worms once you open it up and try to repair things. Otherwise give the owner the option for updating to something more service tech and owner friendly.
    This is V-2 rocket technology and not what you call simple in design or sevicing! 20 plus years of service with this unit (with minimal problems) means it owes the customer nothing and replacement is inevitable.
    Not to long ago I read an article by Dan H. that suggested that replacements be made every 15 years to keep up with technology. The advancements made this past 20 years have been phemnominal and the current trend of higher fuel costs will only feed this movement.
    I remember one customer who had there boiler room under the dining room, the Pulse drove them crazy because it vibrated their china. We replaced that one with a high efficiency Weil McClain about two months after the pulse install.

    MP 1969

  • KenKen Member Posts: 1,640
    Yeah. Me too.

    I installed about 20 and still maintain 6. Although I did not install the six they are each close to 20 years old and run well. They used to make them in north Jersey until Mestek bought out Hydrotherm some years ago.

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  • Boiler GuyBoiler Guy Member Posts: 585
    MP 1969

    V 2 technology. I haven't heard that for a long while. I still have original drawings from the predecessor of the Hydro Pulse. This unit was manufactured in Winnipeg< MB Canada under the Pulsamatic brand name. (1952- 1966) I still service 4 of these units dating back to 1953. I actually have an operable unit in my shop just for nostalgia. How familiar are you with this technology?
  • Boiler GuyBoiler Guy Member Posts: 585

    If you can get the model and S/N I can probably find original service literature on the unit.
  • mp1969mp1969 Member Posts: 226
    Boiler Guy

    I remember that the word V-2 was used when we were certified,other than that I was unaware of the predecessor to the Hydro-Pulse (we were told that the technology came out of Europe.)
    You sound like the Wall's resident expert when it comes to servicing these turbines.

    [email protected]
  • Boiler GuyBoiler Guy Member Posts: 585
    Expert ??

    Well, let's put it this way. Because of my work with the predecessors I worked with Hydrotherm pretty closely on the original launch in Canada. After that I sorta became the "go to guy" all across central Canada. Those were some interesting times. I even have some old letteres from the Lucas Rotax Corp in Germany on the initial applications. And ... If you are inclined to watch discovery or learning channel they have had some old segments on the production of the V-1 and V-2 rockets (called buzz bombs) used during the wars. Some pretty interesting stuff actually.
  • jerry scharfjerry scharf Member Posts: 414
    It's a V1 not a V2


    You just don't know your aviation history. The pulse jet "buzz bomb" was the V1. The V2 was a true rocket and was silent after the inital burn. V2 was much more effective and accurate thanks to Dr. Von Braum, who went on to lead the NASA rocket propulsion group. The Saturn 5 used to launch the moon shots was their grand achievement.

    A house just down the street from me has a new hydropulse installed less than a year ago. Within a week after they moved in they were complaining about the noise. I just shut up and nodded.


  • RangerRanger Member Posts: 210
    PulseParts.. or Jerry Wagner @ 732-560-1001.
  • BoilerproBoilerpro Member Posts: 1,231
    I have several myself

    I installed an AM-100 in a church about 6 years ago and only have had one problem, the blower motor failed. I also have 4 M300's about 17 years old that have had virtually no repairs and service, been subject to no flow, bounced for a year off thier safeties when the step controller failed. You should have seen the condensate flowing when 1.2 million btu's of condensing boilers were running on a new Tekmar 4 stage reset control!

    I still think it is one of the best designs on the market. High water content design,virtually no pressure drop so large energy wasting pumps are not necessary, the blower only runs at start up so virtually no inefficient electricity is used in operation, relatively few parts, no igitors or sensors to go bad, inherently self regulating.....the unit just won't run if conditions are not right.... so additional safties are not needed, and low temp combustion produces very low pollution levels.

    I suspect if you look at the total energy used by the many condensing boilers are there, including the completely ignored use of large amounts of inefficient electricity, it is probably the most efficient boiler on the market, with the possible exception of the Dunkirk Quantum Leap, and maybe the Viessman because of thier two heat exchanger designs..... primary condensing and secondary heat recovery from exhaust.

    I wish they would talk to Lenox about how they controlled the noise on the Pulse Furnaces. At least the exhaust outdoors is nearly silent when using far the quietest of any power vent I've ever heard.

  • Boiler GuyBoiler Guy Member Posts: 585
    OK Jerry

    I'm just a boiler guy - not a history buff. Sorry. But, I thought the initial start on the V-2 still used the V-1 technology? BTW Now that you mention it, I remember seeing the Von Braun name in some of the very old papers I have. Thanks for the lil nostalgia trip. Contact me directly if you would like to discuss this further.
    [email protected]
  • jeffjeff Member Posts: 545

    I'm surprised it is still working. I abandoned those things 15 yrs ago. One of those good ideas that didn't work.
  • Wethead7Wethead7 Member Posts: 170

    The guy you want is Kevin Hay at Comfort Sales
  • TedTed Member Posts: 272
    2 winters ago we replaced 3

    HP,s that were only 12 years old with 2 Vitodens 230 MBH in an office building. This was for the Manasha, WI electric utility company. The guy in charge of the building tracked the therms used based on heating degree days. The first winter it gave them 34.5% fuel savings over the old system. That was about $4,000.00 for the first year. He said less maintenance and added fuel savings will pay back the installed cost of the system in less then 5 years.

    Viessmann rep for WI.
  • WhalenWhalen Member Posts: 1
    Hydrotherm Hydropulse

    I have a Hydropulse by Hydrotherm that was installed back in the '80's (I guess?) by the owner (who was an electrician) before me. The installer didn't do that great a job of installing it. For example: The house has 4 zones but only 1 bleeder. Plus it was installed into a very small room in the basement, which has made repairs very difficult. As a result of issues like that I am running into problems. I really would appreciate someone knowledgable on the subject to come out and take a look at it and to give me some good advice as to the proper repairs. Also I really could use a proper Hydrotherm Hydropulse manual that would provide correct methods to repair that which needs to be repaired. I would also like to talk to someone and get an idea of the affordable cost to replace the existing boiler to something that would be reliable for a long, long time and fit into the cramped room which this boiler fits into. Thanks
  • Jean-David BeyerJean-David Beyer Member Posts: 2,530
    house has 4 zones but only 1 bleeder

    That is not necessarily bad, but I suppose you need safeguards...

    My house has 2 zones plus an indirect fired hot water heater. It has no bleeder at all. It does have a purge valve for each zone, and they might act as bleeders, except that the upstairs zone is higher than the purge valve. When the contractor was installing new baseboard emitters upstairs, I asked why no bleed valve, and he said baseboard does not need them. Does not seem obvious to me.

    Now where the makeup water comes into the system there is an air removal separator

    that presumably removes even dissolved air. So long as water flows, it should be able to remove all the air. It would fail if there was so much air that the circulator could not overcome it.
  • Sorry

    How did we get-off topic on this Hitler stuff?
  • SteamheadSteamhead Member Posts: 11,327
    Regarding Your Quote

    "Not to long ago I read an article by Dan H. that suggested that

    replacements be made every 15 years to keep up with technology"

    I highly doubt most American consumers will stand for that. They expect their new boilers to last the way their old ones did.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • AS59AS59 Member Posts: 2
    I have one!

    I just installed a 5 year tune up kit in my boiler.  How important is it to check and adjust the gas regulator?  BTW, mine is from around 82' and still has the original micro switch controls.  I've installed a three purge fans and two spark plugs since 1992 when I got the house.

  • Tim McElwainTim McElwain Member Posts: 3,895
    If the 5 year called for

    checking the regulator then it should be done. This however should be done by a professional.
  • drum boilerdrum boiler Member Posts: 1
    Hydropulse Quandry

    We have two Hydropulse AM-100's in our system, installed about 1992.  The noisier one still works, although it's a little rusty on the bottom due to a loose condensate drain fitting (now fixed).  The other, usually more trusty, one has been dead for some months now.  It tries to start, but won't quite catch.  I have a tune up kit, but can't get the very rusty spark plug out.  The gas valve/regulator on this one has been replaced about 3 years ago.  The fans on both have been replaced numerous times and are getting expensive (now ~$300).  I'm reticent to sink any more money into this unless I can get someone really confident and qualified to work on it.  We need to do something before heating season fast approaching.  We got thru the worst of last winter on one boiler, but fortunately did not below zero days in a row. 

    Otherwise it's probably time to install a Triangle Tube.

    Anyone Hydropulse lover/specialist out there service SE Michigan area?
  • HydroManHydroMan Member Posts: 14
    Hydro Pulse discontinue

    Due to the inherent issues related to "Pulse" boilers, Hydrotherm discontinue their HydroPulse line a year or two ago. They have replaced it with their KN line of condensing boilers. You may find more information on the KN series boilers at Hope this helps!
  • AS59AS59 Member Posts: 2

    I got my manual online at
  • rp58rp58 Member Posts: 1
    Hydrotherm Pulse

    Anybody out there still crazy enough to use one of these Buzz Bombs? Just changed out 3rd heat exchanger last week. Have kept this 150 running since 91. If it's making noise that means its working!
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