HeatMaster G7000 vs G10000?

I am planning to order my first outdoor wood boiler within the next couple weeks. I’m debating between the HeatMaster G7000 and the G10000.

I purchased a large mostly one-story home in the Lakes Region of New Hampshire. I will be heating 4,500 sqft of living space. The home is unusual and is almost like 2 homes in that the original house has a separate oil-fired forced air heating system (listed at 75k btus) with a water heater in one utility room and across the house is a 150k btus oil-fired forced air heating system with another water heater feeding that half of the house. The 75k btu half is a split-level with 3 bed / 2 bath, a den and a downstairs room and part of the large kitchen, the 150k btu half heats the living rooms and six bedrooms and the other half of the large kitchen.

I am planning to cut heat exchangers in to the plenums of both forced air units and also heat the hot water heaters using heat exchangers. I’m figuring one loop to one utility room and another loop to the other room.

I know the 150k btu side is much better insulated, but it’s still old construction (1980s) with a slab foundation and the other side (split level side) has a crawl space and not nearly as much insulation.

So, a total of 2 hot water heaters and 2 heat exchangers in forced air systems, in Lakes Region NH. If I assume insulation is fairly poor, can the G7000 still handle this or should I be looking at the 10000? Please note that most of the home is a single story, lots of roof on this place, with a split level area on one end.

Thank you all! Excited to get started on this project…

PS: I’ve heard these gassers like to be pushed hard, which has me leaning towards the G7000, but I want to future proof this investment as best I can.

Also, I have access to a large amount of well seasoned wood, so that won’t be an issue.

 

Welcome to FHC Rando...in my opinion not only can the G7000 do the job, I'd say you might could do it with a G4000. My dad put a G10000 in and its a beast...he heats 2 old farmhouses and 2 good size shops with it, and most of the time it is loafing! I tried to talk them into the G7, but they were worried that the G10 was already too small (came from a large CB boiler) turns out the G7 would have been fine 99% of the time.
You are correct that they like to be pushed too.
Do you know how much fuel is typically used in a given year now? If so you can calculate BTU load from that.
Calling some HM owners... morningwood , Farmchuck , lukem

 

I have an older heatmaster GS400. I had to go back and look, but the output is 232K BTU/H...so it falls inbetween the 7000 and the 10000.

We live out in the cornfields where it is ALWAYS windy in a 1960 brick ranch house with a basement. We have forced hot water radiant panels upstairs and cast iron radiators in the garage and basement. 1,800 sq ft upstairs, same downstairs, 500 sq ft garage. Good but not great insulation, all new windows.

The boiler doesn't even begin to break a sweat in sub-0 weather...and I could easily load it one time per day in that weather. That's with a very large family that likes to take very long showers, wash our clothes in hot water, lots of dishes, etc. I probably burn as much wood making DHW as I do heating this place.

They like to run hard and run often. The harder you work them the more efficient they are. Last thing you want is for them to run for 20 minutes and sit for a couple hours. In reality, mine is too big. I'm eventually going to hook my shop up to it, even then it will be too big.

Do what you want to do, but I would be getting the 7000. It's more than you need for now, but you could still heat an out building down the road if you wanted to. I absolutely would run dual line sets...one for each water heater HE and plenum HE as you mentioned. Make sure the water heater gets heat first, then the furnace.

You could probably get by with a 4000 if you plan on some insulation improvements, but that's probably cutting it too close.

 

Thank you! I used the following calculator to enter the amount of fuel oil the previous owner went through per winter and it told me I would need 9.9 cords of wood per year for an 82% efficient wood heater. I recall the G7000 being listed at around that efficiency somewhere…

https://woodboilers.com/biomass-fuel-cost-calculator

PS: The oil company reported that the previous owner used about 1,400 gallons of heating oil per winter.

 

Thank you very much for the information! Do you recall how many plates you ordered for your hot water heat exchanger? I too have a large family and I have no idea how to size that part of the equation. The furnace side was straight forward as the largest size that would fit was just larger BTU-wise than the oil-furnace’s BTU rating, which is what the dealer recommended.

Is there a chart somewhere showing household size to # of hot water exchange plates, or some formula I can use…?

thanks again!

 

With W/W heat exchangers you really can't go too big, but you can go too small. I have a 30 plate exchanger that gives literally endless hot water. I could have done a 20 and probably gotten by, but the 30 was only $25 more and gives me a lot more capacity.

 

Hello Rondo. We purchased a G10000 in December to replace our aging Central Boiler 6430 . We heat 2 houses & a milk house. The Heatmaster definitely cut our wood consumption considerably but it does require more maintenance than our old boiler. We have wood that was testing between 12/18% moisture cut in 2019 & it appears to be working well with the exception of more creosote in the firebox & on the fan impeller than I thought should be building up. I had take the fan out during the heating season & clean the crud of it because it was restricting it from turning. I had to do it again in May. I was a bit disappointed. I guess for me the jury is still out & I guess I’m still learning the stove.

 

That is likely largely caused by "too large" boiler...a G7000 would have probably idled less and run cleaner...dads G10 has only had the creosote issue when the boiler was "overloaded" with wood, in warmer weather. You might be able to set the idle timer to fire the boiler a bit more often, as long as there is enough load there to keep it from boiling over when doing this...might just need to experiment a bit to see how often and for how long you can "bump it", this info is in the "idle timer" settings...on page 30 of the manual that I have downloaded, under "instructions for editing control settings"

 

Thanks I will have to look into that. When I contacted Hestmaster & explained our heating requirements they chose the 10000 over the 7000
Perhaps I didn’t explain our requirements correctly & it is a bit to large.

 

When the weather is borderline too warm and I know the boiler is going to spend the better part of the day idling I'll run up to 180 then turn it off for the day, then fire it again in the evening. 200+ gallons (probably closer to 300 in the whole raidant heat system) of 180 degree water is plenty to keep the house warm for the day. Restarts in 20 seconds with a plumbing torch...then a long hard fire to get it back up to 180 really helps keep things clean. Obviously you have to be home to do this, but I'm home most mornings and evenings so it isn't a big deal.

Even if you don't do this every day, every once in a while you need a long hard burn to keep the firebox and heat exchanger tubes in check, especially when you are idling it a lot.

 

Would increasing the O2 setting eliminate some of the creosote I wonder.

 

If your wood is good n dry you want less air...here, this is clipped from page 34 of the manual...
"Set o2 % This parameter allows you to set the target oxygen level in the exhaust of the furnace. In general, the lower the level of oxygen that you can maintain while burning clean, the more efficient your furnace can operate. Burning seasoned hardwoods at 15%-25% moisture, you may be able to burn clean with an o2 setpoint as low as 3%-5%. If your fuel is less than desirable, i.e. softwoods, higher moisture content wood, woods that are very volatile, wood that is dryer that 15% moisture. You may need to increase the target o2 as high as 6- 8% to achieve a clean burn. If you observe your furnace smoking regularly throughout burn cycles you may have the target o2 too low or too high. If you are making changes to the o2 setpoint, change by 1% at a time and observe the change over a period of a few days."

 

+1 for a G7000.

+1 for the largest plate exchanger you can afford. Personally I have a 20 plate ( 80k BTU supposedly - more like 40K BTU if you talk to the experts ) and it has zero issues heating 40° water to 130° in one pass. I'd recommend getting your water - air HX from these folks, they don't sell any cheap Chinese junk.

Last but not least, do NOT skimp on the lines from the boiler to the house. The money they charge for lines is tough to swallow but you'll end up burning a lot more wood with a cheap wrapped line set. I bought my line from the dealer when I bought my stove. If your boiler is a pretty good distance away from your house, I'd highly recommend doing a delta T analysis to make sure that a standard 1" line set it up snuff. Plan on spending around 2 - 3k ( probably closer to 3k in your case ) in HX's ( water - water and water to air ), pumps, and fittings. I did an install of a G4000 last year, and I had about 2k into that stuff on mine. I did go SS with a lot of stuff when I had the choice though. I did add a few dollars but not much. Sometimes SS was cheaper than brass.

 

Thank you all for the information! Much appreciated!

I’m looking at buying the RhinoFlex line that HeatMaster sells as well as their W/W and W/A heat exchangers. The dealer I’m working with doesn’t seem to sell anything else, like pumps or fittings, so I’ll be buying those elsewhere.

I’m going with the G7000. The wood I have is testing at 12-14.5% moisture content so I think I’m set there.

Still a lot of unknowns, but hopefully it’ll all come together before winter. There’s a local Central Boiler dealer who does everything… moves the boiler to its final location, plumbs in the heat exchangers, everything. My nearest HeatMaster dealer just sells the unit, I have to move it off the trailer and get everything else done myself. If I had more time this sounds like a fun project, but I have a lot to get done to this new house before winter, so I’ll hire some of this work out…

Edit: I forgot to mention that I went with 30 plate W/W heat exchangers. Hopefully that will leave us well set!

 

I recommend Grundfos pumps. Mine have been bulletproof.

 

+1 for Grundfos pumps

Just because they are a dealer doesn't mean they have your best interested in mind. Not trying to sound harsh, but that's the truth unfortunately. I'd make sure what you are buying and paying a premium for is not some cheap Chinese garbage that's going to have issues a few years down the road. The last thing you want to happen is you have Air - Water HX get a hole in it and flood your furnace.

I bought the majority of my fittings through SupplyHouse. They have a warehouse not too far from me, and they are by far the cheapest place to buy them at.

 

[QUOTE="RandoNHFirewoodHoarder, I built a new house and have a G200 installed in my Garage.That thing needs cold weather before its even worth starting up and last winter here in Ontario the furnace blower ran 4-6 hours per day Max. Once iddle time gets to much it seems like a waste.
I also did Not hook up to heat water as with only the 2 of us living here in 4000'house installer said you will pay more for the install( unit etc) than just use electric.as the Boiler only runs 4-5 months per year anyhow

 

I feel like I get more creosote than I should. At 12-17% reading on the moisture meter perhaps our stove is oversized? I call Heatmaster direct & explained our heating requirements & they recommended the G10000
I also found interesting what Lukem posted about milder weather & how his stove performs. Maybe our winter in our area was to mild? I’m considering purchasing another fan motor & fan & having it on hand for a quick swap in the winter when it stops running from build up on the fan blades. Wonder if I’m the only one with this issue? Thanks everyone & good luck with the G7000 Rondo! Please keep us posted.

 

[QUOTE="Farmchuck, I know from my limited Exper that the milder temps and idle time on the unit create more issues and buildup .As other have said they like to run hot so am guessing a fine line between enough stove and not.I know mine get filled only to the bottom of the fire box door even in winter and i burn a combo or poplar.slab wood(ask* maple) and cut up pallets.

 

Thanks for the info Rob. I really appreciate hearing from others. With our stove in the winter a few times we would try reducing the amount of wood in the fire box & usually that would result in the stove shutting down with the low water temperature alarm before we would get back in the evening to fill it. Usually 12-14 hours or so. I’ve read so much I don’t remember which unit do you have? Ours is the Heatmaster G10000
Thanks again for the info!!