can't get enough heat out of VF3000

Hillside · By: **Hillside** On: Wed Nov 21, 2012 11:07 am

the air is open about half way ,,, feed rate is high only way to keep temps as high as it is. When temps outside stay above 32 I don't have a problem the stoker cylces like it should ..

LsFarm · By: **LsFarm** On: Wed Nov 21, 2012 11:12 am

I don't know the design of the heat exchanger, or the inside of the boiler, is it prone ot collecting fly ash and insulating itself?

Member Coalkirk heats a large house with one of these boilers.. It should easily heat 1500sqft.

Are you heating the oil boiler with the VF3000? if so, is the chimney flue on the oil boiler warm or hot??
What can happen is since the boiler is warm it warms it's chimney, creating draft, then it looses heat up the
chimney..

Sometimes a bypass loop needs to be installed and adjusted to get the boiler up to temperature.
Or just slow down the circulation rate.

We need more info about your system, Your radiation is called baseboard , measure the total length of finned tubing you are trying to heat.

The barometric damper will control the draft if it is excessive, this lets too much heat up the chimney instead of being in the boiler. What is the flue temperature ??

Greg L

Pacowy · By: **Pacowy** On: Wed Nov 21, 2012 11:13 am

Hillside wrote:the air is open about half way ,,, feed rate is high only way to keep temps as high as it is. When temps outside stay above 32 I don't have a problem the stoker cylces like it should ..

I'd open the air up all the way and adjust the feed as needed so that even after a long run you get the 1-2" of ash before it drops off. Right now it sounds like the air restriction is holding back your output.

Mike

Rob R. · By: **Rob R.** On: Wed Nov 21, 2012 11:36 am

Pacowy wrote:
Hillside wrote:the air is open about half way ,,, feed rate is high only way to keep temps as high as it is. When temps outside stay above 32 I don't have a problem the stoker cylces like it should ..

I'd open the air up all the way and adjust the feed as needed so that even after a long run you get the 1-2" of ash before it drops off. Right now it sounds like the air restriction is holding back your output.

Mike

I second that motion. Open the air up and increase the feed until you can't maintain ash at the end of the grate during a long burn...cut the feed back a little to re-establish the ash 'ring' at the end of the grate. Once you've done that, double check the draft at the breech and fire door.

Flyer5 · By: **Flyer5** On: Wed Nov 21, 2012 12:14 pm

This is a general rule it may be a little different for the Harman so check your manual.

The combustion air should be set to -.01 to -.03 somewhere in that range some where about .02 less than the stove pipe draft. You need to check that through a hole in the base or door of the unit You should also have about -.04 draft on the chimney or close. Or what ever Harman recommends. The max feed setting is just that set it so you have as much fire without the hot coals jumping overboard.

If you have more combustion air than you need you will waste heat.

Pacowy · By: **Pacowy** On: Wed Nov 21, 2012 12:37 pm

Flyer5 wrote:This is a general rule it may be a little different for the Harman so check your manual.

The combustion air should be set to -.01 to -.03 somewhere in that range some where about .02 less than the stove pipe draft. You need to check that through a hole in the base or door of the unit You should also have about -.04 draft on the chimney or close. Or what ever Harman recommends. The max feed setting is just that set it so you have as much fire without the hot coals jumping overboard.

If you have more combustion air than you need you will waste heat.

Agreed that if it turns out wide open gives too much air he might have to dial it back some to get the amount of ash specified in the manual, but right now his problem is too little output that seems to be related to too much air constriction. The Harman manual covers draft testing and levels for this unit. It does lead to the question of whether the unit was installed with a barometric damper.

Mike

coalkirk · By: **coalkirk** On: Wed Nov 21, 2012 1:19 pm

We need pictures. Something is very wrong. You said your home is well insulated. Well insulated is a relative term. Give us more details. How about your windows? I'm heating more than twice the square footage with my VF3K no problem I don't even have a vent pipe on my oil boiler so I'm not cheating with oil.

KLook · By: **KLook** On: Wed Nov 21, 2012 1:36 pm

Overfire draft I think is .02 for the VF3000. I adjusted my flue to .04. There is a lever on the bottom of the combustion area that needs to be "worked' occasionally. I always did it when the blower was on to blow out the fine ash under the grates. That is another way to prevent the air from getting to the coal. I would have the air at 100% until it was obvious that it could be cut back.

kevin

Flyer5 · By: **Flyer5** On: Wed Nov 21, 2012 2:01 pm

Pacowy wrote:
Flyer5 wrote:This is a general rule it may be a little different for the Harman so check your manual.

The combustion air should be set to -.01 to -.03 somewhere in that range some where about .02 less than the stove pipe draft. You need to check that through a hole in the base or door of the unit You should also have about -.04 draft on the chimney or close. Or what ever Harman recommends. The max feed setting is just that set it so you have as much fire without the hot coals jumping overboard.

If you have more combustion air than you need you will waste heat.

Agreed that if it turns out wide open gives too much air he might have to dial it back some to get the amount of ash specified in the manual, but right now his problem is too little output that seems to be related to too much air constriction. The Harman manual covers draft testing and levels for this unit. It does lead to the question of whether the unit was installed with a barometric damper.

Mike

The feed adjustment will determine the amount of ash. It should have very little ash with no hot /red coals going over the edge. You need to get all 95,000BTUs out of the unit. Combustion air will alter the burn rate but you still want to stay close to MFGs recommendations. To little air you will get incomplete burn, To much and you will waste heat out the pipe.

coalkirk · By: **coalkirk** On: Wed Nov 21, 2012 2:08 pm

Actually this boiler is rated at 95,000 and I believe it is under rated.

Flyer5 · By: **Flyer5** On: Wed Nov 21, 2012 2:17 pm

coalkirk wrote:Actually this boiler is rated at 95,000 and I believe it is under rated.

Thats what I said . LOL

Hillside · By: **Hillside** On: Wed Nov 21, 2012 2:55 pm

The boiler was installed with a barometric damper and adjusted per harman manual. The house is 2x6 walls, insulation between studs, 1/2 in plywood entire house, 1 inch blue foam on the entire house, part of house covered in brick the rest vinyl siding, the windows installed in 1990 were special ordered from Wisconsin as they were the highest rated windows at the time of the build, the ceiling has 12 in of insulation in it. I am not heating two of the bedrooms as I live by myself and don't need them right now.

steamup · By: **steamup** On: Wed Nov 21, 2012 3:31 pm

Do everyone a favor. Please get out a tape measure and check the area of your house.

Do a heat loss for all heated areas. Follow the link below and do a block load.

What's your heat loss?

Where is the boiler?

Is the garage heated?

I see a walk out basement. Is that heated?

You need to count all areas that are heated or should be heated, not just lived in.

Those areas not heated created a load on those that are to be heated.

It looks to me that you could be trying to heat more than 1500 square feet.

Air infiltration is the greated heat loss - usually over 50% on a well insulated house. I see two chimney's in the picture. Do you have a fireplace and could the fireplace damper be open?

Rob R. · By: **Rob R.** On: Wed Nov 21, 2012 3:45 pm

It would also be nice to know what the btu rating is on the oil boiler, and how many feet of baseboard are installed.

sterling40man · By: **sterling40man** On: Wed Nov 21, 2012 7:15 pm

Did you say you heated with the VF last winter? If so, did you clean it out after the heating season.......vacuum out the horizontal sections of the flue pipe (if there are any)..........take a small drill bit and clean out the holes on the grates..........vacuume under the grates? Just throwing that out there.

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