Micro CoGen.

I have a similar system,eko wood boiler,500gallon propane tank for hot water storage and Yanmar diesel chp.
You want the hot water supply from boiler into top of tank and return from bottom.
Supply from yanmar goes into top of tank and return draws from a point approx. 1/3 down from tank.
I did this so the yanmar didn't have as much storage water to work with and allows it to get it up to a more useful temp.

Alot depends on what your heat emitters are, baseboards need alot hotter water than infloor radiant.

Does that ebay regulator have a separate voltage sense line?

This is the the one I am using, http://www.ebay.com/itm/Marine-Advanced-Alternator-regulator-with-upgraded-software-/200923664443?hash=item2ec7fbd03b:g:WVAAAOxyVLNS5mAc&vxp=mtr
Works as intended charging 48v battery bank, but voltage setpoints are limited the a few options via dipswitches.
Sometimes it loads the alternator right away and sometimes it delays like it's suppose to, not sure what the problem is.

The fleet I worked for had several trucks with that delco alt. with the red voltage adjust plug, brings back memories of younger days!

Think it would with no problem.
This regulator has pre set charging profiles,but you can choose FLA ,AGM .
The absorb setting is 14.7V so 58.8V on 48 volt system and it does that easily.
The balmar regulator with all of its adjustability would really be the way to go.

Thanks,yes in the winter here they sell the winter blend #1 & #2 red off road diesel.
That engine doesn't hardly smoke at all.
I have over 1000hrs on it now and it is usually down half a quart of oil when I change the oil every 200 hrs.

Recently replaced the generator head with a 160 amp leese-neville alternator to directly charge the 48 volt battery bank instead of going thru the inverters charger.
Its a 7700 series alternator with external field brush connections so wiring up an external regulator was a snap. The regulator is a DC power systems regulator similar to balmar but with less adjustments available.
Running it @6400rpm puts out 85-95 amps @50 volts.
Eliminates all issues of the inverter syncing with the generator and then dropping it when hit with a big surge load.
Have run it about 25-30 hours,guess we'll see how long it goes.

I replaced mine with a 40 uf and it maintains voltage better.
Surplus center is where I got mine.
Keep in mind the cap is located such that the cooling fan pulls air across it to keep it cool.

I replaced the plastic end cover on the head with a metal breaker box and left enough space along side for the cap to get all the airflow that the cooling fan draws in.

Back in the day I took care of a small fleet of stepvans with 6.2's.
They were generally good for 175,000-200,000 miles.  Pretty much a disposable engine.

More than one,usually when mated to a manual trans, died with a broken crankshaft. Seems they used a cast crank or nodular iron or something,wasn't forged though.

My guess is running one with half the piston-rods will have the same results. At low loads though who knows?

But hey if you have one to try without much effort or cost give it a shot.

Update on the Yanmar.

So I have some not so scientific,but long term operation fuel consumption and BTU output numbers for review.
Almost a year ago I ran it out of fuel (not on purpose) so I thought it would be a good time to keep track of the amount of fuel I use. I put exactly 5 gallons in my transport containers every time I filled them. Now I know that this is not as accurate as weighing consumption,but I buy it by the gallon so this is close enough for me to get a good idea of my operating cost.

So on the 21st- 5 gallon fill I ran it out of fuel again, on purpose this time. It used 105gallons and ran 198 hours, which comes to .53gal/hr.

Now naturally my kwh meter died,and it took me awhile to replace it.But since replacing it I average 4.8kwh per hr. This also is really close to what the Combox(monitoring system for the solar system)reports. As of lately I have been loading it down to more like 5000-5500 watts.

On the heat output,I did a btu test a couple times,when the storage tank was down around 100F. The generator cooling system and exhaust HX are tied into the 500gal. water storage tank via a flatplate HX.  EGT at head was 730F and temperature after exhaust HX was 335F ,with 5500watt load.
Both times the total  btu/hr came to 29000-30000 btu/hour.

I did end up removing the spring loaded belt tensioner ,and just tighten the belts with sliding the gen head in slots. I found that the XW6048 inverter qualifies the generator input better this way,I suppose less belt deflection and more stable frequency.

Any ways it keeps purring along nicely,making me heat and electricity. The little yanmar has 625 hours on it now,still uses no oil to speak of between changes.

Addition; Should note that 90% of the fuel I used was 70-30 mix winter blend. Slightly less btu/gal.

I found a new radiator on amazon for less than $30.
Look in the automotive replacement parts section,and narrow the search to the 70% off items. It might take some searching. They must discount them deeply if they sit there to long.
The one I got fit a Honda Accord but most any of them would work with a little tinkering.
I also got an electric fan pretty reasonable.
Amazon also carries a hayden electric fan switch that is adjustable.

I run it at 2650 rpm. It handles 4500-5000watts with ease.
Tried to post a picture of the plumbing but it won't allow a jpeg?Worked last post so don't know whats up.
Did a 6 hour run today and here are results;
Hours run-6hrs
KWH's produced-27kwh's (measured with utility type meter)
Water storage tank mixed temp start  122F  ending mixed temp 162F rise of40F  tank is 500gallons so 500x8.3lbs gallon =4150lbs X 40=166,000btus/6hrs=27,666btu/hr
I am keeping track of total fuel use over a longer period of time so I have no numbers on that right now.

The flateplate HX I am using is a 40 plate,but I believe a 30 plate would work ok but doesn't hurt to oversize it.

Here is the latest version on my cogenerator.It's a surplus center Yanmar 2tnv belt coupled to a HF 7200 watt gen head.
I ended up remounting the engine and gen head on a more stable platform.Actually it's a old electric ride on pallet jack that i originally bought just for the battery.So it isn't the prettiest but very stable.
I also mounted both the engine and gen head solidly and used a belt tensioner.The engine does sit on 4- threaded stud transmission mounts to isolate some vibration.
One mistake I made was I put the tensioner on the tension side of the belts instead of the slack side,but it seems to work fine as is.

I used a stainless steel swimming pool HX for the exhaust HX.Same one SPS used on their system.It really works well. It and the engine cooling system are plumbed in parallel thru a flat plate HX with the other side of the HX plumbed into the boiler storage tank that heats the house.

I think the best improvement I've made is isolating the exhaust HX with flexible couplings between it ,the engine and rest of the exhaust system.

The HF gen head has worked ok.When I received it the plastic on the end cap and the voltage regulation capacitor was damaged but they sent me new ones.I finally figured out that the capacitor has to be in the exact mounting place as it is located by the air intake vents to keep it cool I suppose.

Although I don't have any numbers yet,I believe I am getting considerable btu's from the system when running 4500-5000 watts into the inverter-charger.

It's been a fun project but always more fine tuning to do yet. http://youtu.be/yhG_h8LF1q4
Can't get the video loaded so I will add some pictures

Nice setup DR
My Yanmar has close to 300hrs on it.I changed the oil at 50hrs and now it is just down halfway to the ad mark.
Watch your exhaust pipes,mine cracked from vibration,I need a longer flex pipe inbetween.
What rpm do you run the engine?

I have one and works good.It came with the rear plastic cover broken from shipping so I called them and they are sending that and the capacitor out no charge.
I will let you know if they come.

As far as working,I have used it approx. 2 -3 hrs. and so far so good.It's connected to my Xantrex 6048 inverter and the inverter syncs up fine with it.
The previous head I had was a Mc-allte 5000 watt and had issues with low voltage until I replaced the capacitor,then it was ok.But the inverter would spit it off when a heavy load first came online.

I paid $500 for the McAlte so could almost buy 2 of the HF heads.

If you do get the HF head,check the wire connections under the end cover.Mine had a plastic 4 wire connector with 1 wire not pushed in completely.Come to think of it,the Mc-alte head had a loose wire in it too.Gotta double check everything.

I have a Mec-Alt(spelling?)from that same supplier belt driven to a 2TNV Yanmar.
Henry is right on with his rpm recomendations. I run mine at 2640rpm and I think that would be the minimum for a good load.
Mine normally runs 4000-4500 watts thru the inverter-charger.
I have found that the voltage(from the gen head) drops quite a bit when loaded over 4500 watts.Sometimes down to 95-100v.Then the inverter spits the generator off.
I may try to re-pulley and get the engine up to2800rpm or so.

i watched the video again and have a question.

Would the exhaust HX be more efficient and work better if the engine exhaust went thru the center with the coolant surrounding it?

The egr coolers that I was going to use have the exhaust going thru the center small tubes with the coolant around them,so just wondering.