Hello all,

Movin' on with this boiler installation here in Denver City, CO . . .

I've been studying the installation diagrams and reading the copy in the install manual .pdf and have some questions regarding our options with fresh-water makeup:

As part of the pre-work for the boiler install, we got into the walls and cut out as much of the old galvanized domestic water pipe as possible (scale was wreaking havoc on every strainer and small orifice in the system).  It's been replaced with 3/4" copper for supply & 1/2" stubs under 10" to each outlet.  I plumbed in and capped a 3/4" stub on the off chance I might need it for the boiler, which leads me to the question:

The diagrams show the makeup water line and pressure reduction valve plumbed at or near the expansion tank, and the copy indicates this is pretty much required.  The EXISTING fresh water makeup is in the CRAWLSPACE (more a sit-space, at 6'x7' and 4' deep) and enters the slab DIRECTLY via one of two cast-iron pipes dangling down.  Should I discard the old fresh water makeup plumbing in favor of a line that runs as the diagrams indicate?  Why the heck would the makeup be plumbed into the basement in the first place?  Might the BOILER have been originally installed in the dirty-assed, completely unfinished crawlspace?

Thanks to everyone who's offered help so far and to everyone who's weighed-in on other informative threads!

charlie

Should I discard the old fresh water makeup plumbing in favor of a line that runs as the diagrams indicate?

Yes, and do some research on boiler piping your still missing air separator.

It may have been piped by DIY er who did not know what he was doing.

Thanks, geo. I'll be capping that line, then. There's an anti-drainback in there, at which I assume I can plug & redtag without draining the whole floor into the crawlspace (creating a muddy, rusty soaking tub).

Nearly everything was included in the existing install, just placed differently. The air-separator is on the boiler-input side, at the highest point in the piping, while the expansion tank was piped on a 1/2" line with ball-valve from a tee on the boiler-out side of the piping.

The diagrams for the munchkin also indicate "closely spaced tees" that tie the boiler-in and boiler-out sides of the piping. This was omitted. Is it a newer idea? Help me with the hydraulics on this concept: What is the reasoning behind having your floor plumbing in a continuous loop with the boiler tied in on a spur loop? Does this type of piping REQUIRE two circulators so water is being pushed through the floor? It seems to me that a single circulator would try to push water in both directions once in the floor, at worst just running water backwards across the closely-spaced tees and back into the boiler.

I'm trying to do piping research and am having a tough time finding photos of actual installs on a system as simple as mine (single zone, 1000 sq. ft. slab, boiler ABOVE radiant piping). Is there a good source that explains the basic hydraulic concepts around modern mod-con boiler piping? I'm not the type of person to accept "cuz that's how it's done" as an explanation.

thanks again,
charlie

Your going to need some basic understanding for hydronic piping and there's too much to cover in this forum.
Forget the pictures look at diagrams.
To help you understand them I highly recommend  a book called "Pumping Away" by Dan Holohan.
Easy to read and understand you will thank me for the suggestion.

Here is a link

http://www.heatinghelp.com/categories/Books/5/5


I wish you good luck!

geo,

Thanks for the advice. I've got the book on order from hh.com.

This is a boiler replacement, not a design & install, though, so I'm not going to have any control over the in-floor piping. Actually I don't even have a way of KNOWING what's in the floor, as we're three owners out from the original purchaser and the last ownership ended up with HUD. Hopefully I can decipher enough, with guidance, to end-up with a reliable and safe system!

charlie

*edit* geo, I had no idea what a resource you'd tuned me into!  I spent some time fishing thru the articles in the resources section.  LOTS of food for thought there!  THANK YOU

The in floor part is a whole new ballgame but the boiler piping has to be right.
If your going to do the piping yourself you might as well understand how and why you pipe it correctly.
It's too late for proper design but at least you will have control over boiler piping.

"May your leaks be few and your heat be plentiful" 

geotek,

Started digging around in our closets and discovered a bunch of valves I'd not noticed (back when our heat worked and we filled the closets with crap). I'm guessing now that there are zones for each room and that the valves are for balancing? They appear to all be wide-open - the slotted screw is aligned with the axis of the pipe in each case. When the wife's mom comes to visit, I'm going to have her bring my father-in-law's metal detector to see if I can get an idea of where the loops run. Mostly just for my own information, but it could be cool!

thanks again!
charlie

They very well may be balance valves.
The more you know about the system the better.
Pictures are nice.

Our camera is visiting Canon for repair. Once it's home, i'll post some photos . .

Geotek,

Thanks SO much for the suggestion.  "Pumping Away" is GREAT!  I've got a much better idea of the way things work now!  I'm still not sure about primary-secondary piping, given the extreme simplicity of our system, the lack of a domestic water loop (and its 180* water requirement), and the relative durability of a stainless-exchanger modulating-condensing boiler.  Now it's a matter of picking the proper pump!

Thanks again, geo.  This book will be making the rounds with a couple of my curious friends, one of whom has a sears package boiler that's getting ready to go Tango Uniform!

charlie

It is all about about flow.
Primary secondary is not always needed if recommend boiler flow is maintained.
Mod con is most efficient with low return temps.

Here is another link for you.

http://www.radiantandhydronics.com/...nd_Fix

Geotek,

Thank you once again for an amazing resource. You're one of the few experts on this forum who pays attention and doesn't simply talk over and around a question without really listening!

I've just started picking through the radiant and hydronics site but it looks like there's some good, plain-spoken info there.

So is a higher delta-T desirable with a mod-con? This would seem to make sense if one is trying to provoke condensation, right? 50* is probably extreme, but one could conceivably shoot for 30-35*? Do you know anything about the Taco microprocessor-controlled Delta-T pumps? Seems like an ideal solution, as you plug in the Delta-T you want and the pump does the rest. . . However, I'm confused as to whether the boiler is capable of controlling the pump speed, or if one has to set the speed manually (as in a regular B&G or Taco 3-speed).

More research . . .

Thanks Again!
charlie

sorry, just examined some literature and it appears that the boiler has no control over pump speed, just whether it's on or off. So the Delta-T might be a good idea, then!

More food for thought.
If you used the return for heating domestic hot water you would see a bonus benefit.
Lowering the return temp and getting some hot water too.
A buffer tank with a heat exchanger to feed your existing would be one option
also the mod con could be your DWH.

I make no claims to being a hydronic expert.

The boiler delta T is dictated by the factory spec. Easy to burn up a ModCon for lack of flow.

Read the Munchkin installation manual on line.

Make DHW with an indirect.

Use the MC50 which will still be too big.

Learn how to set the ODR for your climate.

Have a proper heat load done.

Consider a direct vent condensing water heater with HX and sub-system.

BTW, I attended Redrocks Community College in 1988 where I studied plumbing, hydronic heating and solar.

The Radiant Panel Association headquarters has been in Loveland, CO for the past decade or so.
I am a hydronic expert and know there are many on the front range also.

Like the guy that gets 15 bids for his tree trimming...a lot of time is wasted.

BB,

Yeah, after doing a little looking, it turns out most of the people with the word "Hydronic" on their website are up north a little bit (Loveland, Ft. Collins, Greeley). I suppose I'm being a bit Denver-centric in my search for expertise. Wouldn't be the first time! Do you have any contractors to recommend? You clearly know what you're talking about and if you were here, I'd have called your company at the START of this whole firestorm!

I've read through the munchkin install manual a few times, usually searching for something specific. I think I'll print out the .pdf and do a little light reading before bedtime this week.

Do you think it makes sense to get rid of the steibel-eltron tankless then? The thinking when we installed it was that we'd eventually get Solar PV and produce energy to feed the 'lectric heater, but that project is pushed WAAY back at this point ("pie in the sky" is the phrase, I believe). It's brand new and treats us okay in our itty-bitty house. Also, Dana suggested that the 80k model would have the horsepower to better run an indirect, is this a non-issue? What about feeding the tankless from a low-temp indirect kept at like 120*, using the tankless to bump the temp up the rest of the way? Maybe needlessly complex . . .

if the tankless works, and you're happy with its operating costs, and it's electric, no need to replace. Leave space for an indirect if you need one later but save the cash on the tank, you'll never save enough to pay for it unless your electricity is very expensive and you use a lot of hot water.

an MC50 would require some indirect sizing to make sure your indirect, in the future, could handle your load, but I do agree with badger that sizing the boiler for the load is by far the most ideal choice.

if solar is a goal, solar to heat is a much more efficient and cheaper path than solar to electric to heat. for DHW, especially, thermal DHW is very achievable and your electric on demand makes an IDEAL "boost heater".

Boiler need rarely be "sized" for indirect water heaters. That is a different formula easily confused with "tankless" water heaters.

I look for the cheapest source of fuel and build my system around that. Electricity is ususally the most expensive as it has to be "made" from another fuel source. But I have to admit that I will own one soon as the "off peak" interruptable eletric rate beat the current natural gas rate and is half the cost of propane.

The only advantage a tankless electric water heater has over a super-insulated eletric tank type like the Marathon is space savings.

Find your cheapest fuel and build your system around it as I do for my clients local and beyond.

Since boiler circulators typically use less than a hundred dollars a year electricity other items should be of more concern and at any rate dictated more by the boiler chosen and the distribution system in place.

Save the thermal imaging etc. for the SYFY channel, it's only a thousand square for goodness sake.

hehehee

@BB: Yeah but it'd be FUN! Sorry, have I mentioned I'm a bit of a gearhead/gadget enthusiast/geek? If I made real money I'd need a three car garage . . . Not for cars . . . I should still have someone flow test, though, right?

Space was a primary reason to go tankless for us. Also there was the "endlessness" of the water, which is nice. I've never had a super-insulated ANYTHING in any rental I've ever lived in, so . . And now we've got sunk cost. Think it'll be staying for now.

@Rob: Thanks for reminding me about solar DHW. I'd thrown that baby out with the bathwater when we discovered what we were really looking at for solar space-heating (just don't have the room for a big enough water tank - the dream home will be built with a big-ole cistern for thermal mass, but that's neither here nor there). What remains is to get the wife over the "sex appeal" of PV. Maybe I can put a small DC system in her studio and keep her satisfied . . . Her argument is that PV would provide energy for an array of uses. Mine is that the biggest use of electricity HANDS DOWN in our home is the water heater. I'd rather go with cheap(er) and efficient.

charlie