Installing an indirect HWH

FranklinD

I'm waiting for my 11 year old Richmond power vent (50 gal) water heater to die...everyone tells me it doesn't have long to live, despite never having had any issues with it at all. No moisture, no staining, no corrosion anywhere, but it never hurts to plan ahead. So I've started saving for an indirect to go with my new-ish boiler (a Burnham ESC4 - 78k btu output).

What concerns me is that my system runs at the bottom end of the boiler's allowable temp range (about 130*...which irritates me as a boiler bypass was part of the installation, but wasn't done...long story). So the boiler is piped direct to the system, with a Bumblebee circ displaying 10gpm (constant speed 2...I picked that based on Steamhead's converted gravity system sizing chart article). The radiators all heat evenly and quickly.

Looking at the Burnham I&O manual, at the way they have the optional indirect piped, makes sense to me (they show the system piped with a boiler bypass, with the indirect taking its feed from the boiler side of the bypass). But if an indirect (running high-temp water of course) is piped in to my system as it is now, when the indirect cycles off and the boiler reverts to space heating, I run the risk of dumping 90* return water (in large volume) back into a 180* boiler. That worries me.

So if I re-pipe to exactly the way it's shown in the manual, with the bypass, I assume I'll be okay since it limits the volume of cool return water going through the boiler...assuming it's adjusted correctly. I make that assumption since that's the way the manufacturer has it drawn in the book.

Other than that, the only other option would be Primary/Secondary piping, which would require me to purchase another pump (for a total of 3: boiler loop, system loop, and DHW loop) and to find a way of controlling the system circulator.

Thoughts? And also, anyone have any particular favorite indirect tanks? Are the Burnham Alliance(?) tanks any good? I was previously quoted for a 32 or 35 gallon...I know that these tanks recover a LOT faster than a standard tank. We've never had any issues running out of hot water with our current tank. We only have the one full bath (with standard tub), a dishwasher, and a washer we only use cold water in (4 person household).

I appreciate any real-world advice you can provide. This site is the greatest resource in the world! Merry Christmas, Happy Holidays, and Seasons Greetings to all, and to all a good night!

unclejohn

I wouldn't worry about the return water temp that will occur at change over from DHW to CH. Your indirect will take less then 15 mins at most to heat up. Not much difference from a cold start on the boiler. I like Triangle Tube Smart tanks. I would also recommend a mixing valve.

FranklinD

I appreciate the responses.

In regards to the 90* return water, I just meant if the heating system water is at about 90* once the indirect is done heating, and then there is a call for space heating...I wasn't sure if the difference in temp could hurt the boiler in any way. Once it runs for a few minutes, the return temp does hit 110*...never goes much further, though. Hasn't been a very cold winter here (yet).

Just worried about hurting my new boiler, as the manual has dire warnings about returning too much/too cold return water (thermal shock).

All the new near-boiler piping is 1-1/4" copper...I would use whatever size pipe matches the indirect's ports of course.

When I do the indirect, I've decided that I will repipe to the exact manual specs in terms of the boiler bypass...just seems like a better design than what I have (straight-through the boiler), considering that I have what Burnham is probably defining as a 'high water volume' system. I've computed the capacity out to *roughly* 100 gallons, maybe a bit more.

I've looked at literature on the TT tanks as well, and a few others. I've got some time to decide, thankfully. Lots of info out there.

Thanks!

jonny88

To my knowledge the ES Burnham models are made for low temp return water hence the odr selling feature.I like to put bypass to stop condensation in chimney.Alliance is a solid tank made by Vaughn but has tremendous headloss.Mixing valve is recommended so you can store water at a higher temp(legionella)and will give you an estimated 15 more gallons.
good luck

icesailor

"" All the new near-boiler piping is 1-1/4" copper...I would use whatever size pipe matches the indirect's ports of course. ""

Some Indirect coils come as 3/4" but to get the listed output, they need to be piped 1" or the size that the manufacturer of the tank says to use to get the required rating AND have a boiler rated to deliver that same energy to the indirect coil.

SWEI

Do the math and you can determine the proper pipe size. The indirect manufacturers provide head loss charts, and (though it took awhile) I managed to get Cv values from HTP.

icesailor

If you have a 80,000 BTU gas Mod/Con like anything noted here, It won't matter if you pipe it 2" CTS, you can only get 80,000 BTU's minus efficiency loss into the Indirect..

If you have a 200 HP pick-up truck towing a 1,000# trailer and load, you might make it up the hill without downshifting. Try the same with a 10,000 trailer and load and you WILL be downshifting. It takes Horsepower to pull that load. Nothing else will do. You can shift all the gears you want, it still only has 200 HP, minus the HP needed to just turn over the engine to run itself. Whatever is left over is used to get up the hill or make hot water.

icesailor

"" Boilers have no gears. ""

Sure they do. If the other end was set up to work where the boiler modulated UP when the inside temperature dropped, like when you change settings on a thermostat, a boiler is just like a truck engine. I asked them at Veissmann school why it doesn't do it. They said that 200's computer will do it if you set it up. 100'S aren't smart enough.

If the computer can figure out that the system temperature needs to go up during a outside temperature fall, it should be able to tell that the system temperature needs to go up if it is falling INSIDE too.

You need to understand how aircraft engines get their power and transfer it and not "Lug" from underspeed from too much load, and not destroy themselves in "overspeed" when the load goes away Put a hand throttle on the 200 HO truck and set the speed at one RPM. Drive around. See how well it works.

The truck probably has an automatic transmission and shifts the gears to match the load. The boiler computer runs the automatic transmission. There's a part missing. The part that UPSHIFTS back up when the speed or load decreases.

Don_197

I love it..........the old "Torque vs Horsepower" argument that I see on my car club discussion boards......only with boilers and jet engines....... AWESOME!!! LOL!! 8-)

FranklinD

Wow! Busy for a day and the comments multiply! Excellent!

I'll have to see which indirect tank I like... I'll do some more research this weekend.

Another interesting point I noticed is that the install manual for the ESC changed in mid-2012 I think. The old manual (I downloaded it) has 6-7 pages of piping schematics, while the new one only has 2 schematics, one for zoning with pumps and one with valves. My system is just the one zone, plus the future indirect.

I appreciate all the comments, and the truck/jet engine comments are pretty interesting. I've been a Ford master technician for a decade, and now work on heavy equipment and the police fleet for our city after leaving the dealership life.

I finally managed to get to my mom's house to get some more pics for my 'Old House' thread. Hope to update it tonight.

jonny88

Hatterasguy,the way I see it and I stand to be corrected is if I come out of supply and put a 11/4x1/2 tee with gate valve on supply side and on return leave another tee and tie them in wont the water flow through the path of least resistance being the boiler.If you put a heel tee with temp gauge on return of boiler you can adjust temp by throttling gate valve.Again I only do this for flue condensation but if I am wasting my time and money I will gladly pipe direct.Take care out there

SWEI

A direct-injected turbodiesel comes about as close to full modulation as you can currently buy. Full authority electronic valvetrains are just around the corner.

SWEI

Hatterasguy said:

All diesels are modulated by definition. You give them all the air they could possibly use and modulate the fuel.

Right -- and when you add a turbo, you get variable displacement on top of that.

icesailor

The wonders of computer driven turbocharging.

FranklinD

Right before my departure from Ford, I spent one last week at the Twin Cities Training Center and got to see the new (at the time) 1.0 liter 3 cylinder gas engine. Direct Injected, turbo'd, cute little guy. LOTS of balance-shafting done to keep the vibration in check though.

I enjoyed working on the standard Ecoboost engine (3.5) as well. The one thing that always bothered me was how loud the direct-acting valve trains are. And the darn-near square cut cam lobe that drives the high pressure fuel pump on the valve cover. WOW is it noisy.

The city PD fleet I maintain has 9 new Explorer-based Interceptors (and they're still holding onto 7 Crown Vics, my personal favorite). The Explorers all have the 3.7 V6, quite a snappy little engine. Starting to see some interesting issues related to fuel control on them though. The 4 units that are over 4500 total hours are starting to eat fuel injectors, and if the officers don't report the Check Engine light soon enough, they'll eat the corresponding catalytic converter as well.

I do miss being on the 'forefront' of the technology, but boy I don't miss the 11 hr days, cranky customers, deadlines, and missed suppers every night. Now I get to help my kids with their homework after school and help make dinner...wouldn't trade that for anything.