Soot in vent pipe - hydroflex 60

This is my first year with a harman hydroflex 60 boiler piped I to my baseboard heat and direct power vent. Has worked well for the first 2 tons of pellets this year and have been running the feed rate at 4. Had cold temps this week and boiler wasn't keeping up so I increased the feed rate to 6 and I notice a black soot outside at the exhaust vent and the ash in the stoves black rather than the grey / white it has been. Stove didn't seem to keep up any better. Also did a cleaning of the stove and noticed the twirly things (technical term) in the heat exchanger tubes were also black. It doesn't seem like this stove adjusts the air flow when the pellet feed rate is adjusted, true? Do people adjust feed rates when it is colder outside or just leave them as-is for a particular fuel? Is the soot a result of too much fuel and not enough air?

Thanks.

When it comes to burning and combustion the mixture is the key, basically air and fuel... After burning 2 tons of pellets how well did you clean the stove? Black as you know is bad and can form/cause creosote problems which will cause a chimney fire. Creosote is formed when the exhaust or smoke does not escape fast enough and forms that nasty "tar" looking stuff. One of your ratios is off, either its not pulling enough air (cleaning) or not getting or getting too much fuel.. You don't need to turn the stove up to six, 4 or 4 1/2 is ideal... How many square feet are you trying to heat? how old is your home?

Thanks

Ryan

The Kitchen and Bath Shop

Ryan-

Thanks for your reply. I have cleaned the boiler every 10 days or so, vacuumed the tubes, cleaned the burn pot, etc. Since I posted, I got a 3" dia brush and cleared the power vent (exhaust) and it had some debris in it but not a lot. My home (2,300 ft2) was built in lYe 1970s and is 2x4 construction but we've done quite a lot of insulation and a blower door rest showed it is pretty tight.

I talked to the Harman dealer and he asked if my makeup air is from outside, which it is. Apparently he's seen problems on real cold days having outdoor air go into the burn area enough that they don't recommend it. (they sold me the boiler but someone else installed it).

For now i've turned the feed down to 4 and it is a little warmer outside and the black has gone away. Sounds like I should leave the feed on 4.

Doug

Well your dealer is crazy, having a cold air intake actually will boost efficiency of the stove a couple percent... It would have to be DARN cold to actually effect it.

If you want my honest opinion I would never sell someone the hydro that was sitting on 2,300 square feet of space.. Its just going to have to work way too hard to maintain that level of heating on cold days.. PB105 would have been a much better fit if the space allowed it.. Anyway, you don't need an air intake in that home... You need a back up source of heat that can pick up some of the slack for they hydro.. Hope I helped

Ryan-

Thanks for the feedback on the outside air issue, good to know. As for the size of the unit, i do have a backup propane unit that comes on automatically when the hydroflex can't keep up. I also level load my heating in the house by not doing setbacks so the boiler isn't asked to heat the entire house 5 deg' just maintain where it is. Finally, you are correct that part of the decision on the hydroflex was space. I also have a little experience with the pb105 and know it had some control and feed issues.

Things seem to be working better now with the feed rate steady at 4.

Doug

Hello Doug G,

I also live in VT and installed my Hydroflex-60 Pellet Boiler last summer (2011). We have been burning it all this winter, with no problems. I've been running my Hydroflex 60 on speed=3.5, which seems to be the sweet spot for the pellets that I have and able to keep up with my house heat loss. Although, I did burn at speed=4 for 2 days when it was below zero.

So far, we have burned LG, Cubex, and Greene Team pellets. I like the Greene Team pellets the best.

Have you had any other problems with your Hydroflex-60 ?
Do you have a prefered pellet ?

Thanks for sharing your Hydroflex 60 experiences !

VT_Bubba

VT_Bubba -

Good to connect. My HF60 has been running great all winter as well. I use New England Wood Pellets (http://www.pelletheat.com/) exclusively and keep the feed rate at 4.2 and don't change it. No problems and it has kept up with heating all winter with very little (<20 gal) propane burned as backup.

The only issues I've had is the heat shields inside the boiler (on right and left of burn area) warped and, on the right one, actually had a hole burned in it from the combustion. Harman gave me 2 new shields and mentioned that they don't put the spiral plates in the center 6 boiler tubes in new boilers to fix this problem I took them out of mine although I also had new heat shield plates made out of Stainless Steel which are much better at the high temps.

I had the refractory that sits on top of the burn 'tongue' disintegrated in the first year. Harman replaced that under warranty.

I do have one last thing which is the cast iron piece that the above mentioned refractory sits on is degrading. Just noticed it a few weeks ago so haven't mentioned it to the dealer yet.

I'm generally please with the unit. I love the small footprint and while it's had some issues, the Dealer (Stove Depot http://www.thestovedepot.com/) and Harman have been very good to work with.

Doug

Hello Doug,

Thank you for the reply ! While I'm somewhat disappointed to hear about some of your HF60 problems, I'm very pleased to have found another HF60 owner in VT. I will certainly keep an eye on the components you mentioned and will post on this forum if I have similar issues, or something that may be interesting to you.

Nice meeting you and thanks again for the reply !

VT_Bubba

When the Harman dealer showed me the Hydroflex60 the other day, he showed me that the turbulators (correct term?) in the middle of the group weren't installed, but didn't say why. Does efficiency take a hit?

Velvetfoot,

As you probably read in the post above from Doug, he makes this same comment to me in his post. This was the first that I had heard of removing the 6 inner "turbulators". For what it's worth, Harman shipped my HF60 in April 2011 and it had all of the Turbulators installed and I have been burning all winter (maybe 2-Tons) with all of the "turbulators" in my HF60 and have not had any problems.

I would expect to have some efficency loss without ALL of these turbulators installed. The question is how much ? I'm guessing its small, like maybe 2-5%, but that is just my wild guess. In the end, even a 5% loss would not be very bad and that would still put the HF60 above most boilers and/or pellet appliances.

I wonder if Harman has adjusted thier published +90% efficency numbers (Gov Tax Credit requirement) ? That would be a good question for Harman and/or your Harman Dealer...

VT_Bubba

Velvetfoot,

I E-mailed my Harman Dealer and ask them about the removal of the 6 Inner Tube-Spirals.

My Dealer E-mailed back, stating that they new nothing about that issue and called Harman to enquire. Harman stated the Issue was the burning of those spirals and there was a 4% efficiency loss with those 6 spirals removed. I told them that I was running on feed rate = 3.5 and I was leaving the spirals in my HF60 and they said that was OK.

VT_Bubba

4% is nothing to sneeze at. I wonder if they give you the spirals, if only as extras.
I have to say, my dealer doesn't seem to be anxious for a sale; maybe that's a good thing.
Other things go through my head too: maybe he's reluctant to sell the unit..

I've been busy at work and cutting up a tri-axle load of logs and also putting in a Field Controls automatic vent damper for the oil furnace, but I'm still thinking HF60!

There's a home show this weekend that I'll be going to. Maybe there'll be some interesting things to see.

Doug G.

thanks for the post. what size is your home? type? so em i right that the feed rate of the pellet is more to match the "type" of pellets rather than increasing the temp? the temp would be controlled more by the time the unit it run? ie the longer it runs at temp the warmer the home will be. the pellet feed rate would be more for the needed ratio to burn the specific pellets used. correct?
i ask because im looking to buy a HF60 to heat my 1700 sqft ranch. that is 2x4 construction, if your HF60 is keeping up with a larger home than mine then it may be the right choice for me.

thank you.

Hello Steelman,

Doug comments above in his posts that he is heating about 2,300sqft in VT with his HF60 (It's Cold up here...).

I'm heating about 1,900 sqft (2x6 construction floor1 and 2) + 650sgft in the basement (woodstove). But, I burn my Woodstove which heats the basement and maybe 70% of my floor-1 heating. My HF60 heats about 30% of floor1, 100% floor2, and my DHW (when the Solar can't do it in Dec-Jan). Personally, I think some folks are using these HF60's, when a PB105 would be more appropriate for the size of thier house. I would have a PB105, if I had the space to accomodate that unit in my boiler room.

The Harman Feed Rate is primarily determined by the pellet type you are burning, but increasing the Feed Rate does make a bigger fire, giving more heat to the water in the boiler. It's really about how much water is circulating through the boiler and can the boiler keep the temp with that cold water load. My HF60 burns very nice on rate=2 to 3 (the sweet-spot for my pellets), but if both zones come on at the same time (100ft of baseboard) the HF60 can't keep the temp up at that low feed rate. For my house, with my pellets, I need to run rate=3.5 to have a large enough fire in the boiler to keep the temp up with both zones running at the same time. Several of my friends burn thier PB105's on Rate 1-2 , but most of them circulate water all the time ! From what I see, the lower the feed rate on the boiler, the better the burn, as long as your boiler can stay above the min temp setting while servicing your biggest heating load. You do NOT want these boilers running below 140F !

Depending on your house efficency, climate, and multi-boiler system designcontrols, I think the HF60 would be good match for a home 1,000-1,700sgft. Just my Humble Opinion....

VT_Bubba

IMHO, I think you or someone should do a heat loss of your home to determine if the Hydroflex 60 is going to produce enough BTU's to heat it, without the use of the propane furnace if this is what you desire.

http://www.pexsupply.com/pex/control/BTUCalculator?intcmp=calc;btu-rc

I just purchased a Harman Hydroflex 60 boiler and am looking for anyone who also has this boiler to share ideas on it's functionality. I'm using it as a primary heat source with an oil backup. It's also heating my DHW. I've had some issues with venting but I hope I have all that worked out now. I've been trying different pellets (Lignetics, Hamer and New England) and different feed rates to keep it at it's highest efficiency but am still using more pellets then I originally thought I would. Thoughts please. Thanks.

My house is a colonial and just under 2400sf and is well insulated. Last year I went through about 1000 gallons of oil in a very mild winter.

I've had my Hydroflex for 2 winters now, using as primary source of heat for extremely tight ICF home (2900 sq ft) near Green Bay, WI. I used 2-3 tons/ season and am happy with the HF60. Other than the draft blower failing(warranty?) in year 2, I burn fir pellets and do a weekly scrape an and vacuum. I burned pine the first year and had to scrape daily. Using feed rate of 3 and thermostat 175-145.