EKO with a primary loop

[Chris S]

When I installed my system i did not want to use a thermostatic valve for boiler protection, I decided rather to use an additional circulator with a Tekmar control.
Because I have 2 recycled tanks in my system I was concerned about sediment & debris, and was going to put in a Y strainer, but decided instaed to use a Caleffi hydroseperator. The piping became much simpler, but now that its running for a few months, I'm thinking that the recirculation pump was unnecessary.
I have The EKo controller set to turn on the pump at 160- adding heat into the primary loop. An Aquastat on that loop also set at 160 turns on the circulator that sends water to my storage, and heating loads.
In operation the boiler runs 160-170 and the secondary pump cycles until the return temperature from storage starts to rise and then boiler temperature will rise towards the setpoint. In practice at 190 I no longer need a fire because my storaage is 185.
We have built primary loops for twinned boiler installs ( which mine is), and mod - con boiler installation, and I'm sold on the hydroseperator as an economical way to accomplish primary secondary piping with air elimination.
I'm thinking that it will in my case provide boiler protection as well, eliminating the return loop, Danfoss, or pump and control. I haven't turned off the recirculating pump yet, but I plan to one of the next few days when I can be close to the system and monitor it.
Any thoughts from you wetheads?

 

[hayrack]

I like your setup. I have the Laddomat in my system, but have always wondered why you could not establish boiler protection with a primary loop. You have proved my theory. I am in the process of helping a friend hook up a storage tank and I have been kicking around this idea in my head. He did locate a Laddomat, but I may still try it your way, if not with his then maybe another.

 

[jebatty]

If I'm understanding correctly, you are saying that your primary loop is never less than about 160F, so that the wood boiler return water is never less than 160F. If that's true, then there is little reason to have boiler return water protection. For awhile I operated my system in a functionally similar way, but I still found that the boiler return water protection circuit was an advantage. With 1000 gal storage, and storage frequently meeting demand for substantial periods of time, I am firing my boiler maybe once a day or less frequently, meaning many cold starts. I found that the boiler heated faster and provided 160F+ water to the system faster if I left boiler return water protection "on." By eliminating return water protection and recirculating the boiler/primary loop until the loop reaches 160F, the boiler needs to heat all of its own water plus water in the loop to 160F, which can take awhile, before 160F water is available to the system. With the return water protection in place, top of boiler only needs to reach 160F, for example, before some boiler output is available to the system, with boiler output volume rising as the boiler continues to heat. 6 of 1, half dozen of the other.

 

[leaddog]

I don't think that thermo-syphoning will move the btu's fast enough with out the pump. It should work if you don't have it in full burn but in full burn I don't think it can keep up. But the only way to find out is do it but just stay close.
leaddog

 

[in hot water]

I don't know that you would get protection under all the operating conditions? Try it and let us know, I'd be interested in seeing the data. thanks

hr

 

[Chris S]

I cleaned my boiler yesterday, so the night before, I set the aquastats lower so that it wouldn't be too hot when I went to open it up. As a result, my storage temperatures were unusually low ( 120 top of tank 100 bottom). When I restarted it, I stayed in the boiler room for an hour doing some paperwork. I have a thermometer on the return side of the boiler loop, and saw 140 and just below as the pumps were cycling, so that answers HR's question. I'm not sure if I want to cut in another aquastat to turn the recirc pump off once that temperature is adequate. Doing so I would be running one less pump, saving 50 or so watts.
Looking fwd to next year and dryer wood!!

 

[in hot water]

You can also calculate what goes on inside that HydroSeparator and see the various temperatures under different flow rates. Pages 8-10 at this link show the math.

www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_1_us.pdf


Your flow rates are allowing you to hit that sweet spot as far as return temperatures. I suspect as the tank temperature drops below 100°F or so, that mixed temperature to the boiler return may fall below the required 140°F .

The math works, I'm like you I like to see and observe it happening first hand. Time to put an easy chair along the EKO

hr

 

[Gooserider]

Somebody recently pointed at a very interesting site Comfort-Calc.net that has a lot of good info on it about all sorts of different heating / cooling technologies, some of which sort of contradicts some of the things we try to push hard on here, though trying to meet the same end goals... The link above is to just one of many articles.

One of the things that site's author seems to believe is that rather than doing a "system bypass" configuration like we are generally recommending, where we mostly circulate water between the boiler supply and return, only allowing system water to flow in to that loop as things warm up, so that the system flow is rather slow at first, we would be better to do a "boiler bypass"...

In a boiler bypass, the pump is positioned to circulate water primarily through the system, at full speed, as soon as heat is called for, with a small amount being pulled off to flow through the boiler as the boiler heats up. The argument is that by keeping the system flow velocity high, you get better air elimination, and transport of at least some heat to the load faster... Since the load starts to get warmed as soon as the boiler fires, it is possible that on a shoulder season day, the load might be satisfied before all the system water has even been fully warmed, or at least get a good bit of the way there, so you have a certain amount of inherent "outdoor reset" effect...

He also likes primary/secondary piping with the system as the primary loop, and the boiler as a secondary...

I'm still sort of working at wrapping my head around the concept, but it does seem to make sense to me... I bring it up in this thread because it seems like what the OP is doing could fit either the system bypass or P/S models in terms of function...

Gooserider

 

[Chris S]

Several cast iron fossil fuel boiler manufacturers call for bypass piping in their manuals. In a class that I attended, hosted by a manufacturer the instructor explained that in a system with a lot of water , such as an old converted gravity system, condenstaion is a very good possibility without such a configuration. All of the instructors, and most wetheads embrace P/S piping.

What we now consider a simple system is a 2-6 zones of HWBB heat- fin tube, directly connected to a return header- with zone valves. Supply piping is usually shared as flow allows. In this type of installation, I would not use P/S, but would install a bypass as a precaution, and to protect the boiler warranty if called for.

The systems we mostly install however will operate at 2, or three different temperatures, and so will have multiple circulators. In a case like this, or with modulating - condensing boilers, primary/ secondary piping is easier, and/or required.
Once you start putting all of those fittings together, closely spaced T's etc. you begin to realize that a hydroseperator, or hydrolink really makes a lot of sense. Once you embrace this, getting the flows correct, and troubleshooting really become very easy.

My son has read Dan Holohans books, and understands it, one of my installers who has 20 yrs experience in the field- still doesn't get it, so we make drawings for him. He follows them, but still doesn't know why. The people on this board to alarge extent are all about the why.

 

[stee6043]

Aside from the plumbing discussion - Chris - do you have substantial leaking at your upper door during burns? It looks like you're pushing wood gas out the bottom and top of your upper door seal? I think you would do well to spend $40 on the new gasket from New Horizon and get that sucker sealed up. Just a thought...

As for plumbing - you say you feel this is an "economical" way to accomplish primary/secondary. How much does your hydro separator cost? In the past I've seen units such as this that cost more than a Taco pump, Danfoss valve and Taco separator combined...

 

[Chris S]

I will replace my seals at some point, but what you see in the picture is a result of 1 hr left unattended with the door closed but not latched.
A hydroseperator is more costly than all of what you described. When I consider the cost, I am comparing it to the cost of building a primary loop, the cost of fittings which adds up quickly, plus the labor cost which I always consider.
I built a loop for a two boiler system, with an indirect, and a tekmar control for my brother. I built my system with the Hydroseperator, in less than 1/2 the time, and I believe i almost paid for the HS with savings in all of those 1 1/4 copper fittings. I could almost pay for it in labor savings.
Plus, I like what it does & how it looks