Print

[Schavis]

We had a Hawken Energy GX 10 installed this Fall by a Dealer Installer recommended by the company and things aren't going too well.  Furnace only heats house for 8 hours then I gotta refill.  Most of the piping is 1" red pex piping.  Sometimes in the mess of fittings elbows and tees the size of the piping changes to 3/4"... can this cause problems and reduce the heating ability of the unit?

[Sprinter]

It depends on where it is and what that zone needs for flow. I believe a 3/4 orifice will flow somewhere around 4 GPM at 2 ft/sec.  Remember 3/4" zone valves unless speced full port only have a 3/8" port hole. So you have to calculate what that run needs for btu and at the supply temp will give you how many GPM you need.

BTU=GPMxDTx500
GPM=(BTU/DT)x500

[slimjim]

Increasing the pipe size may help with delivering the heat better but will do nothing to extend your burn times, what did they use for underground pipe and have you checked the heat loss on it, an 8 hour burn is not very long.

[BoilerHouse]

Also; Are you burning good quality hardwood?  Is the heat load too great for the boiler?

[Schavis]

thanks for some of the replies - SlimJim What is a DT?...
Boilerhouse.  Yes, we are burning good seasoned hardwood... I do think it the furnace is too small for the house, but that is the only size that Hawken Energy sells.  So now we are stuck having been sold something that doesn't work for us, they say we need to change out our delivery system - they will do it at cost, but that is rediculous... they installed the furnace on our system and now tell us... we weren't sure it would work, but if you spend more money, it might work?  BAD way to do business... but we have a furnace that will save us money they keep saying... NOT, I feel as though I would have been better burning the $14,000 I paid them...
Sprinter - I will check the heat loss on the pipe today and get back to you.

[slimjim]

DT typically in hydronics refers to to temp difference between two measured points/  supply and return on boiler

[BoilerHouse]

This boiler is apparently rated to put out over 140,000 Btu/hr, and being a gasifier, it is premium technology.  How big is your house, how well insulated, are any outbuildings such as a shop being heated.  Are you using it to heat domestic hot water, and how much wood do you put in each 8 hours.

Also, to Slimjim's point, keying in on the underground pipe, how long is the run, and what type of underground is it, i.e. How well insulated is it, and how well is the insulation protected from water infiltration.

[Sprinter]

A good underground pex supply line will only loose 1 degree per 100' @5 GPM flow. Taking temp  measurements will give a good idea of what's going on. Where the BTUz are going. The more important thing would be how long is the burn cycle when it does call for heat? If that's all that model can do, then storage is the only other way to extend burn times.

[Schavis]

We loose only less than 1 degree from the boiler to the house.. well insulated and buried 3 feet down.. no problems there.  We are heating a 2200 sf house with no insulation and single pane glass windows... yes, also DHW and a small garage to 40 degrees.  We fill the firebox every 8 hours.. whatever we can fit with a little wiggle room in the top.

[Sprinter]

Looking at the chart 3/4" recommended flow 3.2gpm@2'/sec ,,, 6gpm@4'/second. 1gpm=10,000btu@180 supply & 160 return. This is IF you 3/4 pex pipe is upon or that has full IPS diameter. All other pex is 1/2" at the fittings.

So let's say you are getting 100,000 per hour from the boiler and in 8hrs that's 800kbtu minus the stored water in the boiler and your still above 700kbtu used.
If your house is 2200'sqft. Average heat loss of 50kbtu/h (poorly to average insulated) , your either loosing half of the boiler output, wood is much wetter than thought or boiler is loosing heat. Either way it's more than 50% difference/loss.

As far as your temp loss on S&R lines, that 1 degree is only good if your pumping less than 6 GPM. A popular multi wrap pipe brand flows 14gpm thru their pipe to show better numbers. On 1" pex 14gpm is 7.9 ft/second and would hide a 15 degree heat loss per 100' . If you look at any manufacturer specs 4 ft/sec is the most they wanna flow. At 6ft/sec you have erosion of metal fittings and the pex pipe itself. Stated in the Logstor or Urecon specs, also Uponor.  Pex fittings look sand blasted and or melted at the ends. At 8'/second it can wear a copper 90 to failure in a few seasons of heavy use depending on water conditions.  If you can hear the water easily it's too fast.

What kind of delta T do you have at the HE, and do you have a moisture meter to test wood?

[BoilerHouse]

Sounds like you have quite a load on the furnace.  You best bang for your buck would be to get the house insulated if possible.  Less wood in the winter, cooler in the summer.  The silver lining; as much wood as you are using, imagine the $$$ if you were heating with oil or propane.

[Schavis]

@boilerhouse... thanks for the insulation advice... just not practical to insulate the house due to its layout... every room has 3 exterior walls and single pane historical windows too.... yes, even though we are burning alot of wood, we are saving money over oil, but on a cold day I have to fill it every 4-6 hours... so I can't do much else... that includes just getting naps instead of sleep, have to limit my time away from the house, etc.  My life seems to now revolve around filling the furnace ... WAY undersized and Hawken won't stand up and help out, even though they agree that the furnace will not heat us properly....

[cantoo]

Quote from the site---->Our Model GX10 furnace is designed to heat one building similar to an average or larger sized home. You will enjoy putting money in the bank, instead of paying huge heating bills!
 1st problem, according to this stove is too small. Not sure what changing the pipe is going to help unless of course they really messed up the install. If your house is poorly insulated, poor windows and a tough layout to heat then you need an oversized boiler not an undersized one.

[Sprinter]

Many many many owb problems are poor design. Does the unit have a rated output, then rated 12 hour burn btu/hr, 6 hr burn/but/hr rating info at all. You still haven't covered the basics, before you spend a dime or change anything. The easiest fix is to do some math and provide an accurate diagram of the system layout. A plan and a btu load and you could be one post away from a solution. The rest is hearsay until the design or math proves its too small.
By the way what does your moisture meter say on a fresh cut of your wood?