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Harmon HydroFlex 60 Pellet Boiler?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by velvetfoot, Jan 23, 2012.

  1. Matt_VT

    Matt_VT New Member

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    Hi Bubba,

    I've been looking through this 2.4 schematic you mentioned earlier. It appears that when you run the pellet (in the schematic cord wood) boiler the weighted check is opened by the pellet circulator, and the swing check on the oil boiler is closed by the same flow. When you want to run the oil boiler you shut off the pellet circulator, and then your zone circs generate the flow through the oil boiler - is that right?

    I'd prefer to have the extra circulator on my oil boiler. Basically swap the boilers in this schematic. It works out much better (fewer rework) to my existing plumbing, reduces electricity use since I'll run pellets most of the time, and simplifies my powered dump zone a bit (only one circulator to run for dump). Do you see any drawbacks to this? Note I don't think I would run the mixing valve, so that stuff is out of the equation.

    Thanks,
    Matt

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  2. Matt_VT

    Matt_VT New Member

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    Hi, what about an electric boiler for backup? If it's for the hopefully rare event that your pellet unit breaks down, or you're away from home, then what could be more reliable (assuming the power is on)? And I'd guess the cost is much lower than an oil or propane boiler and install. I see some on the houseneeds website, looks like reasonable pricing to me. Sure, operating cost would be high, but as long as you don't use it often it could be easily offset by the install savings.

    Matt
  3. SmokeEater

    SmokeEater Feeling the Heat

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    I'm going to look for those TARM schematics on multiple boiler setups because I may have the whole pdf file. Give me a little time, my computer is still indexing the files to search.
  4. VT_Bubba

    VT_Bubba Member

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    Hello Matt,

    Yes, you understand the design point correctly. I did not want another circulator during Oil operation and that is one benifit of that 1-circ design over a two circ design. I don't see why the 1-circ design could not be used either way (circ on the oil vs circ on the pellet). The key to having 1 circ vs two circs, is that weighted check valve which is required in the 1 circ design. You need to make sure that the boiler flow of the boiler circ, can meet the flow needs of all of the zones, or you will get parasitic flow through the off-boiler when multiple zones turn-on at the same time, wasting heat in the off-boiler.

    However, I think you need a totally different design, which will always circulate your pellet hot water to the oil boiler to keep the DHW coil hot. Your DHW comes from a coil in your Oil Boiler, Right ? You probably do NOT need the mixing valve and you do NOT really need a powered dump loop using pellet (you should have a powered dump for a wood boiler !). The HF60 provides an internal "Over-Temp" relay, which I did wire in parallel to one of my zone thermostat's, so if the HF60 were ever to go "over-temp", it would just turn on one of my zones. Notice that Harman does NOT require a Dump Zone per say, but that may be handy if you plan to run in MANUAL Mode (but that's easy to do with another auqastat that just picks one of your zones as I describe above).

    BTW: Per one of your previous posts, a cold start boiler is used when you have an Indirect DHW tank on a zone (no need to keep the boiler hot all the time). Your DHW coil in the boiler requires "Non-Cold Start" operation to keep that DHW hot all the time. If you added an Indirect DHW Tank, you could change your oil boiler Auquastat and convert your existing oil-boiler to Cold-Start operation.

    I hope that helps ...

    VT_Bubba
  5. VT_Bubba

    VT_Bubba Member

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    Nothing wrong with that plan. Durring the summer months my Solar does most of my DHW work and my existing Indirect DHW Tank can fire the oil if needed, Oil is still cheaper than Electric for heating water. Every situation is different, based on your house use model and existing systems.

    VT_Bubba
  6. VT_Bubba

    VT_Bubba Member

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    Hello Old WetHead,

    Welcome to the forum !

    Solar DHW equipment is pretty much available at any plumbing supply place these days, both Flat Plate and Evacuated Tube collectors. You can also buy Solar kits (Tank, Diff Controller, Panels, Pump, etc...). Most plumbing supply places can also help with your Solar system design.

    My Solar DHW system is NOT Drain Back, it's pressurised glycol, which is typical for a northern install. I did not buy a kit, because I wanted a lifetime SS tank. So, I designed my own system and bought most of the parts at HouseNeeds.com. The HouseNeeds folks were very knowledgeable and helpful, and were also reasonably close for me to pick-up (No Shipping). I'm a self-described high reliability, ease of use, and high efficiency freak. I used 2 Flat Plate collectors for High-Reliability and snow shed, and a Lifetime HeatFlo 80gal SS tank. I prefer 2 tank Solar DHW system designs (80gal Solar Tank feeds my 40gal DHW Tank which is heated with pellet or oil as needed). My solar DHW has been in operation for 4yrs now, without a single problem. I had about $5,800 in total equipment cost, but got the 30% Fed Tax Credit on that, so I have about $4,000 total investment. I figure about 1 more yr for full payback.

    Solar DHW is a great complement to your existing pellet, or wood boiler system ! BTW: I really wanted to super size my solar design to get some home heating out of it. But after some long,deep calculations, I concluded that it did not pass my business case, because of my existing High-Temp Base Board heating system. If you have an existing Low Temp radiant home heating system, then Solar Heating might make sense, but it did not make sense for me.

    VT_Bubba
  7. SmokeEater

    SmokeEater Feeling the Heat

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    I did find those TARM schematics in my files but they are in pdf format and are 4.4 MB in size. If you want, I'll email them. JD
  8. Matt_VT

    Matt_VT New Member

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    Hi,

    I lost track of this post, but I do want to discuss this more, I'm starting to make some summer plans for mods. My DHW is coming from an electric heat pump water heater. I'm going to shut down my oil and pellet furnaces for the summer. The reason I think my oil boiler is not a "cold start" model is what I read in the manual (it's an "Ultimate" furnace). It says you must run hot. If you run it cold start then they require you install an inline thermostat, I guess to avoid thermal shock and condensation, and I don't really want to mess with that. I figure I can use a relay to wire my oil boiler such that it's shut off, but if for some reason the pellet boiler goes cold then the oil will fire up and stay on.

    So, what I'm trying to figure out now is how to size the pellet circulator. Looking at the Tarm document (2 boiler direct design), it seems like if the zone circulators draw more flow than the primary, there's a risk of the swing check valve that goes to the oil boiler supply opening and heating the inactive oil boiler. Does the pellet circulator need to be bigger than all zone circs combined? Or am I not thinking this through properly? I don't want to oversize that circulator and waste electricity...

    Matt
  9. BadgerBoilerMN

    BadgerBoilerMN New Member

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    With a single heat source the primary loop is usually pumped through the boiler and secondary "tertiary" pumps pull water from this primary loop. Solid fuel boilers almost always require high operating temperatures to assure clean burning and avoid "sustained flue condensation", so running typical radiant floor return temperatures directly to a solid fuel boiler is not a good idea.

    The piping for most of these boiler should then be primary/secondary with boiler pump being secondary and the speed of that pump controlled for temperature. With two heat sources it is usually best to pipe them individually to the primary (the pipe taking hot water out to the terminals with a dedicated circulator) so that each may inject heated water to the primary as needed. We have not used weighted check since the advent of integral checks came out years ago. Most of the hydronic system we design use three speed circulators such as Grundfos 1558 and more and more Alpha and Wilos in the mix.

    Keep your boilers water hot and your terminal water cool.
  10. VT_Bubba

    VT_Bubba Member

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    Hello Matt,

    Yes, you are 100% correct. The Primary Loop flow must handle the entire flow of the combined secondary loops, or you will get parasitic flow through the off boiler. In my system, I run 3-speed Taco-00R Circ's with the Heating Zones on Speed1 ( with 3/4" Pipe), with my Primary Pellet Loop using 1" piping on speed2. The pellet loop using 1" on speed-2 can supply enough flow to support Qty=2 Zones of 3/4" Piping on speed1. You can also add some Adjustable Flow Control Check-valves to your zones, to adjust the zone flows down to match the available primary loop flow.

    Instead of the relay, I would use a simple Honeywell L4006A Aquastat located over on the Pellet Boiler, to "OPEN" the oil-boiler circuit if the pellet boiler is ever above 135F. So if the pellet boiler is every below 135F (for any reason....), the oil boiler will be powered as it normally would be. I also use a Honeywell L4006B on my pellet circulator, so the pellet circ will only run if the pellet boiler is > 140F.

    I hope that helps...

    VT_Bubba
  11. heaterman

    heaterman Minister of Fire

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    After readin through all of this I have to ask a question. ......

    Doesn't Harman offer any diagrams on installation or have a tech line that you can call?
  12. VT_Bubba

    VT_Bubba Member

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    HeaterMan,

    No, Harman provides very little information on Multi-Boiler systems. As you know, there are many ways to put together multiple boiler systems, depending on your existing heating systems, your life-style, your budget, etc... But let's be honest here, most Oil and Gas Boiler's don't provide mult-boiler information either. The Harman doc's do show basic hook-up for a single boiler system, just like most other boiler docs.

    You can go to the Harman Web pages and download the PDF file if your interested. From a multi-boiler standpoint, the Harman Pellet Boilers are just like any other boiler from a multi-system design standpoint.

    VT_Bubba
  13. iceguy4

    iceguy4 Minister of Fire

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    I have a PB 105 and love it...It is too big for my house this year but worked almost perfectly. I purchased it early (it will heat another bulding next yer as well as the one it heated this year) to start the savings from the price of heating oil. This unit can go over a week un-attended with a bulk hopper (not reccomended) so what if it is a bit too big ...it will just run less. good boiler IMHO...
  14. VT_Bubba

    VT_Bubba Member

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    Hello IceGuy4,

    I'm happy to hear that your PB105 is meeting your needs. I have read multiple comments about the need for "Daiily cleanings", but take notice that these comments are always hear-say from people that have never owned or used one of these boilers. I have never heard a real owner complaining about cleaning the HF60 or the PB105.

    The HF60 has better access to the Burn-Pot for the every 1-2 day burn-pot scrape (30sec of work when you are adding pellets), but does require additional cleaning of the Heat Exchanger and Spirals about every 2-4wks (30-40mins for a complete cleaning). The PB105 has a massive ash pan and can easily burn 1-ton of pellets before you need to empty the ashes.

    I try to scrape my burn-pot everyday, if I happen to be in the basement and find the boiler in shut-down because of no heat requested from the house. If it's in shut-down (AUTOSTART mode), I always take the 30sec to scrape the HF60 burn-pot when I add pellets, just to remove any crust from the Hardwood Pellets (Softwood Pellets have no crust). I have left my House\HF60 unattended in Zero degree Weather for 3days/4nights, with no problems. Yes, pellet boilers do need attention, but nothing like many have implied.

    BTW-If you see me commenting about the PB105 being "To Big", I'm talking about the physical size of the PB105 and the required space it needs in your boiler room, not the BTU output which is modulated as needed. We are happy with the HF60, but would have used a PB105 if I had the physical space in my boiler room.

    I see your pellet list. What pellets do you like the best, and why ?

    VT_Bubba
    iceguy4 likes this.
  15. iceguy4

    iceguy4 Minister of Fire

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    I cant tell the difference in heat so the best pellet is the cheapest. can you tell the difference. also as for scraping burnpot...when I do a weekly cleaning I have so little crust that I have mooved it out to 2 weeks. My veny and blower needs attention more. I suspect because moving the scraper rods(3) when blower is running lets too much soot go ...thoughts? Also the bulk hopper is the BOMB!!!
  16. velvetfoot

    velvetfoot Minister of Fire

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    Did both you guys vent it out the side of the house?
  17. iceguy4

    iceguy4 Minister of Fire

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    I did.. and glad i chose that option. during cold weather the blower runs most of the time. moving the cleaning rods sends soot tward blower (cuz its running) My blower and vent seem to need cleaning weekly or my unit will kick a code 3 (status light blinking 3 times...ESP out of range) an easy clean project...like 10 min. this time of year I'll bet i cn go up to 3 weeks without even going down stairs::-) I know some here are getting tired of hearing me brag (for want of a better word....for me the bulk hopper is a "no brainer" @ $2000.00+-. It flips the time spent on my boiler...IE 90% of my time spent with my boiler is when I want...not 90% of the time being when it needs me...Iceguy...in control of vertical and horizontal....
  18. VT_Bubba

    VT_Bubba Member

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    Yes, my HF60 is directed vented (No Chimney), with Outside Air-In too.

    Yes, I can tell a difference in pellets. I can't really measure the BTU output of the pellets, but I can tell how the boiler responds under heavy load, when both zones kick on at the same time. In general, some Hardwood Pellets seem to put out more heat at a slower feed-rate, and seem to have less ash and fly-ash in the fan/pipe. However, most Hardwood Pellets seem to create a Crust in the burn-pot, which I think blocks the air flow and eventually effects the air-fuel mixture of the burn if you don't scrape every 1-2 days. I have never had any crust when burning softwood pellets, but they seem to create more ash. I don't get much junk in the exaust pipe, but I do clean the fan about every other cleaning.

    VT_Bubba
  19. velvetfoot

    velvetfoot Minister of Fire

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    I've been thinking about this for a while, and I can see the hf60 fitting in to occasionally heat the man cave basement, not sure how much, and to get the upstairs up to temp. The insert doesn't get the upstairs warm enough on the chilly days. The venting out the side would save a lot of money, and I'm not even sure I could get another flue in the chase if I wanted to.
  20. Doeboy611

    Doeboy611 New Member

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    We are considering purchasing the Hydroflex 60 for our 1600 ft2 ranch. After reading most of these posts I am still unsure what is involved for the process of cleaning these units. It sounds like you need to scrape the burn pot every day or so which only takes a minute or two. What does it take for time, tools etc for cleaning the rest of the furnace? My experience has been with wood and coal stoves which seem to be pretty simple in comparison, but would like to move to pellets to save us time and wear and tear on our bodies. Thanks for your assistance.
  21. VT_Bubba

    VT_Bubba Member

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    Hello DoeBoy611,

    Don't be scared by the cleaning. I clean my HF60 in about 5 phases (depending on how much I'm burning) :
    1) Daily Cleaning (1-2mins) - Scrape the burn-pot and put pellets in the hopper (Far easier then loading the wood stove !)
    2) Every 1-2wks Cleaning (3-5mins) - Empty the ash pan, Scrape the burn-pot, and put pellets in the hopper (Far easier and faster then emptying the ash and loading the wood stove !).
    3) Every 3-4wks Cleaning (10-20mins) - Vaccum the Heat Exchanger, Empty the ash pan, Scrape the burn-pot, and put pellets in the hopper.
    4) Every 6-10wks (2-3 times a heating season) Cleaning (20-40mins) - Clean exhaust pipe, Vaccum the Exhaust Fan,Vaccum the Heat Exchanger, Empty the ash pan, Scrape the burn-pot, and put pellets in the hopper.
    5) End of every Season (1hr - 1.5hr) - Everything in step 4), plus I clean the lower burn-pot, each spiral, and the pellet augar assembly.

    I hope that helps !

    VT_Bubba
    Doeboy611 likes this.
  22. Doeboy611

    Doeboy611 New Member

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    Thanks for the quick reply. The process sounds pretty manageable and I think we will be moving forward with the purchase. One more question. In an earlier post you mentioned that when you installed your unit you also added two additional circulators that allowed your oil and pellet boilers to work in series and independently of each other. Without those would there be operational difficulties? All the shared knowledge is greatly appreciated!
  23. VT_Bubba

    VT_Bubba Member

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    DoeBoy611,

    I think you may be getting confused with all of the multi-boiler installation posts on this thread. My two boilers (Oil and Pellet) are plumbed in Parallel (Not in Series as you implied). This is an installation detail and may be different based on your existing system type(s). Every install is different and sometimes Series makes more sense than Parallel.

    In my parallel install, I added one new circulator to push the Pellet Hot Water onto the existing Oil-Boiler Header pipe, using 2 new aquastats on the Pellet Boiler for control (One Aquastat holds OFF the Oil-Boiler fire when the Pellet Boiler is HOT, the second aquastat turns ON the new pellet circulator when the house wants heat and the Pellet Boiler is HOT). I did this so the new Pellet circulator will only run when the Pellet Boiler is HOT and the House is calling for heat.
    I hope that helps !
    VT_Bubba
  24. Doeboy611

    Doeboy611 New Member

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    Yes, definitely confused - got it now - thanks again!
  25. ovendoctor

    ovendoctor New Member

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    just wanted to say Hiya from Da U P of Michigan [ were it snows 10 months of the year and has 2 months of bad snowmobiling ]

    we just installed a Harman Hf 60 and are loving it,it heats the house nicely [100+ year old] and we heat our DW with a home made pre heater

    electric bill dropped 120.00 for hot water

    Doc.

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