hot water heating

[vdubnut62]

Hello Gentlemen, I have never been the sharpest tool in the shed and if anyone has gotten any impression of the opposite (not very  likely), I am truly sorry!
I have been in the planning stages of my scheme for some years now, I plan to heat my home and domestic hot water with a Tarm water furnace. This particular device requires a heat storage tank.  The recommended storage is 800 gallons, but I have only managed to be able to finagle a 500 gallon propane tank that will be mounted in a vertical position as opposed to the horizontal for which it was designed. The Roid and the Changfoid will also dump cooling and exhaust heat into the system whenever they happen to be needed/running.
 My question is, should I plumb my hot water feed from the furnace into the very top of the tank, or down maybe 2/3 or 3/4 ?  The heated water will be taken from the very top and circulated to the house with the coolest water to the furnace/heat exchangers(for the engines) and the return from the house from the lowest point of the tank. Is this clear as so much mud?
I welcome any and all recommendations or suggestions.
Ron in TN.

[glort]

First thing that occurs is why in the hell anyone would want 3000 Litres ( 800 gal) of hot water???
Even my daughter couldn't be in the shower that long and use that much hot water.... although I bet she'd put in a good dent in it given the chance!   

Are you running a hotel or does this do some sort of Hydronic heating system as well?  If so, does it have a HE from the main tank for the Domestic hot water? I was under the impression that hydronic systems had to have anti corrosive chemicals added and you are using an old LPG tank....?


As you will be using a smaller tank than recommended to begin with, I'd suggest you want all the capacity/ buffer you can get.  If you feed from any point above the bottom, the water will stratify and you will have hot on top and " cold" below and never have a full hot tank. I know nothing about these boilers but I can well see the tank coming up to temp before the boiler can back off and stop dumping heat and you could activate the blow off valve and loose water and potentially stress the system.  I have played around with my oil burning water heater enough to know how that goes and that only had 125L of water not 3000 or almost 2000 which is a huge thermal mass to contend with if  it over heated.  If you went with a partial height feed, I would be putting a circulation pump on the tank to take the hot water from the top back to the bottom if something like this happened.  I can guarantee you a tank will boil at the top with water  way cooler sitting on the bottom. .

Plumbing the hot water into the bottom of the tank would be the way to go I believe. As cooled water returns, it will tend to push the hot water up anyway.  Having the hot water feed at the bottom is the only way you are going to get the whole tank up to the right temp.  Again, for whatever reason they specify an 800g tank, you are already way under with the 500. No need to reduce that any more as it must be for thermal buffer rather than water storage itself for the system.

For the engines  which I get the impression won't be used that much anyway, I'd be taking their feed water from the return line which will be the coolest water in the system. Just put a valve in the line with a "T" so you can shut the water to the engines off when not running or for maintenance and the return water can bypass or be drawn through as needed. You may need a circ pump to push the cold water in and the hot out  or a nice High  exit from the engines to give you some thermosyphoning.  I'd wrap that pipe to make sure the water stays hot and rises and that could go higher up in the tank as the thermal input is only going to be a few Kw anyway.

Are you going to insulate the tank or will it be located in the house so the heat bleed will be where you want it anyway?

Hope this helps!

[LowGear]

This one?  https://woodboilers.com/media/wysiwyg/Downloads/Product_Brochures/Excel_Brochure.pdf

A couple of questions.  How hot does the water get?  What kind of heaters / radiators?

[vdubnut62]

 Gee, I did leave out a few pertinent details, I warned you I'm not the smartest guy around. I thought stratification in a heat storage tank was a good thing? With the feed to the house coming from the top of the tank, I would always be drawing the warmest water.
 For thermal mass Glort, it will heat the house via 100,000 BTU/hour capable heat exchanger, and the garage via a 50,000 BTU/hour capable hanging heater. Flat plate heat exchanger for domestic hot water. Insulated tank in a dedicated building, 2 circulating pumps one continuously running on the house loop, another on the furnace that will run on heat rise. So I guess it will in fact be circulated in the tank. Yes the water will be corrosion treated with a product designed for outdoor boilers, also I will install a big effing anode.
 Yes Casey, very close, but an older design - not a true gasifier, but it does have a secondary burn. The water can be at any temp  from 160 to 200 degrees F, just a matter of turning a knob on the draft control. This thing is advertised to generate (is that the correct term?) an output of 140,000 BTU's an hour, and it is designed to be a "batch" boiler,  the reason for the heat storage tank, so it can burn hotter and cleaner instead of smoking like a train when "throttled down" and ramping back up to a full burn.
Ron.

P.S. Glort, in regards to the Daughter thing...... I have my Wife, Daughter and Grand Daughter living here, I should regard myself Blessed?

[glort]

Given you have enough hot water ( almost) to keep 3 women happy, I'd say you could consider yourself blessed.  I would if there were one more here with us.

With the added detail that this IS in fact a batch boiler and using the water for thermal storage, I stand by the idea of a bottom feed.
In normal operation I don't see it makes much difference with the circulation but it does give you that buffer if it stops or there are other details we may be missing.  The circulation being constant seems a bit wasteful though. I can see a lot of heat being bled through pipes and being lost in places other than heating the home.

I looked it up and am surprised at the power the thing is producing. 140K BTU is only 30 Kw.  I would have assumed more for a wood fire. My fathers slow combustion heater in his house will do that.
None the less, that's a fair bit to throw at a place full time. If the thing is batch burning several times a day, then I can well see why you would need the thermal mass.  Turning the temp up in effect increases the amount of storage which may be useful with the smaller tank.  In my last place I had the hot water dialed up as far as it would go.
The hotter the water the less is used when mixed with cold and the greater the chance of daughter not draining it completely.  :0)
I did change it from off peak to on demand for obvious reasons.


I think wood heater are extremely efficent things.
They keep you warm when Cutting the wood, they keep you bloody worm splitting and stacking it and the keep you warm again when you burn it.
For me, if it wasn't for the comfort of watching a fire burn, it would be way too much work for my lazy arse!
Mrs. wanted to put in a slow combustion here.  I said but my love, as much as I'd love one, we have no wood supply and buying it is very expensive. She gave the idea away knowing I was right till she mentioned she would like one to a mate but we have no wood supply. He Piped up I have more wood than I know what to do with. I have all the gear, he can come cut as much wood as he wants, split it etc. Not a problem!

Yeah, thanks mate. Much appreciated!    If I don't bust a gut doing it for my father I can go twice as hard trying to keep up with the wife and daughter whom I just know like so many others I have seen with fires, would have the place a cosy 35oC with all the doors and windows open while they run round happily in their underwear and burn about a chord of wood a week. 

One thing I'd like to try and maybe should look at prepping now, Paper logs with a twist.
They seem a fair bit of work to produce these things in any real Qty ( although a cement mixer for the pulping the paper and doing it in a large scale would help)  but I have thought of either using oil instead of water to pulp the paper or putting oil on the logs  when they were dry to increase the BTU value.
Don't know if they would bind or fall apart  with the oil but veg dries so if they could be done in summer and left to skin, they should have a LOT more heat value than the paper alone.
Wouldn't really affect the labor input but it sure would increase the heat output!

Anyway, I still think bottom of the tank is the way to go. Every commercially made water heater I have seen does it that way and it would stand to reason to me.

[vdubnut62]

Thanks Glort! Duly noted and catagorized.
Bruce, I'm not looking to save the planet(sorry!) Just looking to offset some of the energy consumed by the Electric Heat Pump by cleaning up damage from the Ice Storm a few years ago.

C'mon guys!!! I'm still looking for input..................................... Hell I'll beg if it comes to that.


Ron.

[LowGear]

Hi Ron,

Not to sound too boring but what does the manufacture recommend?  I know it's in the first chapter of sidewalk superintending to not ask manual speak questions but they have done it before.

I maintain an apartment house that has hot water heat.  Very nice and comfortable heat but quite slow on the uptake.  My apartment is on baseboard heaters or wall furnaces as they're called by the sales brochure.  About 10 minutes after setting the thermostat all is good   16X24 with 6'1" foot ceilings takes some of the challenge out of lift off.  Not with the Buderus.  The main timer is set to come on at 4"30 AM and keep the heat up until late morning.  Then we just rely on the passive solar and the daytime higher temperatures.  Back on as darkness falls until 9:00 PM.  It seems like there are fewer sore throats and skin problems.

At the farm in Hawaii we aren't sure how to close all of the windows and regard thermostats as some sort of dark art from a previous civilization.  Sorry, but I just can't resist reminding folks that it's very lucky to live in the tropics and like today stop work at noon because it was raining and the temperature got down to the low 70s.  Lay back in the recliner with a light cover and the computer tuned in to YouTube.  Not the toughest day this week.  OK, we're at 1000 feet and don't have a thermostat.

[vdubnut62]

Ok men i will have to rejoin the conversation at a later date . We all have the Flu, wife, daughter, grand daughter and me. Sorry,     i will see y'all.

[glort]

Hmm, Maybe you should look at installing some central heating. Maybe something with a wood burner and circulate water around and..... Oh, never mind!

Thank you for you consideration in not spreading your lurgy. It's summer here and there would be nothing worse than catching a flu in the heat.
No idea how I managed it but I went all last winter without getting sick. Miracle really as I was out in freezing winds working my butt off and sweating and would have bet the house I was moving from I would have got sick as a dog. By some miracle, I didn't.

Hope you all get welll really soon. Being crook over Christmas sounds like a real drag.

[veggie]

vdubnut62

Similar to most solar hot water systems, consider the following...

HEATING THE TANK:
From your heating sources (Engines, boiler, and maybe H20solar), bring the heated water into the top of the tank.
Cooler water is drawn from the bottom of the tank and pumped to the heat sources.

TAKING HEAT FROM THE TANK:
For retrieving heat from the tank (To your floor heating system or fan coils), take the water from the top of the tank and return it to the bottom of the tank.

So you would have 2 different loops connected to the tank.

Consider a couple of Evacuated solar water heater panels to kick daytime heat into that tank. Will save you a pile of fuel over several years.

cheers,
Veggie

[BruceM]

+1  My homebuilt EPDM lined 800 insulated hot water storage tank is heated from the top,  and domestic hot water heat is used from the top.  (The copper exchange coils flow from lower mid tank to top.) This gives you faster recovery and the highest temperatures.   My in floor heat system draws from mid tank which moderates the temperature for that system somewhat. 

Sorry about the previous irrelevant to your thread rant- I removed it.

[mr.fixit]

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.

[vdubnut62]

 Well, it looks like we are gonna survive. Tamiflu is some really good stuff.
Thanks to all for the wealth of information!  It was suggested several time that I follow manufacturers directions as to the inlet and discharge locations. There were none!
It was just left from the point of connect a heat storage tank to the boiler. Sorry, I should have made that clear.
So, the consensus is hot comes and goes at the top, cooler or return and boiler feed from the bottom. That is going to be my plan then.
Veggie, I purposely oriented the shed so the slope of the roof faces south so solar was sorta kinda in the "plan". I'm taking baby steps, when, (and if) I get one facet of this thing
more or less mastered, then I'll move on to the next step.

Bruce what kind of temps do you have in that EPDM lined tank?

I sure thought there was a diagram on here that showed a tempering valve in line to the heat exchanger, but it's gone away.  Any suggestions for output temps?
I will be using a water to air exchanger in the air handler of my heat pump. It is supposed to be capable of transferring 100,000  BTU/hr.

Thanks again!!!
Ron.

[BruceM]

EPDM is rated for 170F, but I set my drainback solar pump to stop heating my tank at 140F.  This should increase liner life and allows me to skip the mixer valve, since I don't have to worry about children.

I saw the EPDM lined tank idea on builditsolar.com.  Mine is mostly below grade, hand dug and lined with hardyboard and 3" isocyanurate foam board I got surplus. The hardyboard was just insurance in case of earth movement. I went for the below grade tank to have the simplest drainback solar system possible- just one pump, and a copper coil heat exchanger in the tank.

I use the hot water directly for the home in floor heat; while not pressurized, it works by adding a vacuum tank and brass tube to the Watts air bleed valve.  It removes the air that is generated when the backup propane water heater is run to boost the temperature before going to the house floor; heating water releases the absorbed air.  This allows the use of a wimpy 20 watt DC circulation pump.  More powerful pumps with higher lift and flow can move air through the system.

[LowGear]

This should increase liner life and allows me to skip the mixer valve, since I don't have to worry about children.

Hmmmm;  Selling before becoming mature?  130 at the tap or tub/shower is really hot.