Circulator Pump Mystery

kevink1955

But what happens in the spring and fall when only a few unit need heat. No way that 5 or so 007 are going to fill that large loop with hot water.

Solid_Fuel_Man

@kevink1955 My thoughts exactly.

I am still wondering how much of the heat is lost in the underground piping. It can be very significant! Maybe why one boiler is firing full tilt and only able to keep SWT at 135. Also scale from excessive MU water. Lots of nasties here.

I want to go on a field trip too!

EBEBRATT-Ed

@Charlie from wmass & @SeymourCates There cast Iron boilers. Do you still want to use a 30 degree delta?

But I agree with @Mad Dog I wouldn't put a wrench on ANYTHING until April 1st.

That place could flood at any moment.

To me, the most important thing is the unknown condition of the underground piping.

If it looks anything like the exposed piping.........just don't know

To me this thing is crying for primary secondary. I am not in favor of firing any boiler much less a large one with unknown water flow through it. To me a flame pounding the cast iron without water flow on the other side is a bad thing that shortens boilers lives. 007s indeed

Mark Eatherton

Does your boiler have a cold? A cold makeup that is? Assuming there is only one make up, check t where it goes into the system, and if it is cold, you have under ground leak(s).

Expansion and contraction will KILL copper fittings over time. Back and for the expansion and contraction and eventual fitting failure in the crotch of the fitting. Bad thing is, when its hot, it looses less than when its cold. With that many feet of mains, you are going to need to use a Doppler Leak Co-relator to find its exact location. Once you find it (THEM) you'd be wise to set some anchor blocks and expansion joints and send the expansion towards the blocks.

Good luck Scott. Have bags, can travel...

ME

Charlie from wmass

I'm not saying that I want a 30 degree delta T. I'm saying it might be designed for one. The 30-degree delta T should not bother a cast-iron boiler as long as a starting point of the delta-t is above 135 degrees. I guess I'm reckless enough where I would take one of those or two of those interacts and I would put a Delta-t pump on them and set it up for 25 degrees or 30 degrees I would also try it on the heat zones that are being unresponsive right now if you change out half a dozen pumps that are variable you can at least adjust them to see if it makes a difference in the operation of the system.

Charlie from wmass

A fair Maiden was never won by a faint heart. I would also put a meter on the supply water

EBEBRATT-Ed

LOL @Charlie from wmass faint heart or not I would be waiting for spring!!

Charlie from wmass

I'm so used to nobody complaining about their heating system until the middle of the season it doesn't even matter anymore. Customer I want to replace my wet returns in January and -15 weather. Me okay

EBEBRATT-Ed

@Charlie from wmass I know. I am in the middle of one now. 2 1000mbh condensing boilers. Customer waited all summer did nothing.

Ordered 8" polypropolyne flue................waiting
Oh, it's 10 psi gas??
That means a gas survey, engineered stamped drawing, gas co approval, inspector approval etc etc.........

WHEN ARE WE GOING TO HAVE HEAT??

Larry Weingarten

Hello, I've been watching this with interest. Experience with big underground distribution is that it can lose much more heat than the building loads. I've seen 8X! With the condition of the system, probable poor energy performance, and cost to rebuild, might it make sense to transition to individual systems in each building? There... I said it!

Yours, Larry

EBEBRATT-Ed

@Larry Weingarten that's my concern as well. The underground is worse than what we can see

Charlie from wmass

@Larry Weingarten especially with the compact size and efficiency of condensing boilers it would make a lot of sense but that still means the distribution of gas throughout the complex. I forget who suggested that on the first page but somebody did. If the condition of the piping in the boiler room is any indication as to how is underground throughout the complex that very well meat be the best solution

JUGHNE

Page one, post one....that was me.

They could start with the further building and go for the ModCon route, he thought there were CI rads. So it would be maybe a good marriage.

Say just do the furthest 3-4 buildings. Cut the big loop and install a U-bend return. Maybe the closer units would be served OK. At least 1/3 of the phones would not ring at night.

And the DHW, that would have to have a recir line right?
It would be interesting to check the temp drop at 3AM to see how much is lost to the ground.

New gas line seems simpler/cheaper than digging around those UG HW lines.

You see how bad things are in the boiler room. Imagine how fuddled up they could be UG....knowing this was going to be covered up.......we are done, lets go home!
FWIW

BobC

I lived in the projects as a kid. These were 4 family houses serviced by a central steam plant for heat and hot water. We were the 4th building in a loop of 38 buildings, needless to say the double hung thermostat was used all winter long. Back in the early 50's it was a great place to live, we were out on a peninsula with fields to romp in and the beach was a couple of hundred feet away. In the winter we would sled down a hill and out over the marsh, if wasn't bitterly cold and you went to far you would break through the ice. that was uncomfortable but the water was only 12-18" deep - but it meant you had to go home to change clothes. The wet ones were laid on the steam radiators to dry out. We were all poor but everybody else was so it was normal to us.

The steam plant had two very large boilers (10 -12ft diameter cast iron behemoths that were 15 ft long?) they were run on bunker oil. The oil tank was under the buildings parking lot and was 10-12,000 gallons as I recall. To me they looked like ship boilers but 6 years old it was all amazing. I used to go over there and watch the guys work on the boilers, they seemed to enjoy the company. The plant was commissioned in the late 40's and ran till the underground pipes let go in the 80's. That plant was replaced by individual building boilers in the 80's .

hot_rod

Larry Weingarten said:

Hello, I've been watching this with interest. Experience with big underground distribution is that it can lose much more heat than the building loads. I've seen 8X! With the condition of the system, probable poor energy performance, and cost to rebuild, might it make sense to transition to individual systems in each building? There... I said it!

Yours, Larry

Mini splits, they get heat and AC Maybe at a fraction of the cost if in fact the underground is leaking or losing insulation R value

ScottSecor

I can finally offer some sort of update, looks like the owner wants to move forward in the near future on this project.

I've learned a few things over the winter and I'll try to make sense of it. Just to reiterate, there are currently two W/M 14-88 gas fired boilers that appear to be original to this system that was installed in 1988. The boiler room piping as well as the underground distribution system were installed at the same time. The third boiler, a Buderus G-615 was installed in the last eight years and leaked soon after it was installed, as such it was isolated and shut down mid-season. Despite the overall condition of the two W/M boilers, they passed a brief hydrostatic test after some relatively minor leaks were repaired late this past season.

As suspected there are no boiler pumps or traditional system pumps. After performing many calculations and and observations I believe many of you people are correct, it is actually a gravity system. There are two heating loops, each 4" copper when they leave and return to the boiler room. There is also a 3" loop that serves the five Ergomax indirect tanks, these 3" pipes are only used for dhw. There are 120 apartments, that vary from 1 bedroom units to three bedroom units.

On "normal" pumped hot water heating systems you can flow about 175 gpm through 4" copper pipe with a 20 degree delta T with typical friction loss. I try to design for 4 fps max in most cases, but will go as high a 6fps in basements (and underground I suppose). 175 + 175 = 350 gpm or 3.5MBH. There are fifteen buildings in total, let's assume 3.5MBH divided by 15 buildings for an average of 233,000 BTU/H per building. I believe the heat loss for the buildings is significantly less (more like 150,000 each, tops). I'm going to do a heat loss this week. However as stated by others, the heat loss from the piping is likely significant. For example there is approximately eighty feet of uninsulated of 6" pipe (mostly copper) in the boiler room, keep things pretty warm (year round at this point). I will add that on the three buildings that I could see the supply and return as they entered, all were insulated with what appeared to be 1" thick fiberglass pipe insulation.

As of this moment I'm leaning towards replacing the cast iron boilers with cast iron again, fitted with P/F full mod gas burners. I see very little advantage of condensing boilers for this application as I now know they need at least 180 degree water at design temps. I'm also very concerned with sediment that is likely contaminated the system. I think a large hydro separator will help with air removal and sediment removal. I also plan to install primary circulator pumps for each new heating boiler. I plan on sizing each heating boiler to handle sixty or seventy percent of the load.

Instead of oversizing the heating boilers to contend with the dhw load, I'm leaning towards two smaller cast iron gas fired forced draft boilers for dhw needs. These boilers will be connected to the dedicated 3" copper pipes that go to the small basement with the Ergomax tanks. Thankfully this room is "only" about sixty feet away. This way they don't have to run the large boilers in the summer and they'll still have some redundancy. I've learned that they need 180 boiler water in the colder months as the current tanks are undersized for the peak demand, we'll be adding a few more tanks and dhw mixing valves (there are none now). Each dhw boiler will be sized to also handle sixty or seventy percent of the load.

Most buildings do not have basements (maybe three of fifteen have partial) so installing dedicated heating or dhw system for each s is not practical. Thankfully, boilers are in a dedicated building with a high pressure gas main.

Apparently, the original installer utilized a Heat Timer to turn off every circ pump (120 in total I'm told) when the outdoor temp rises above setpoint (60 degrees). Not too sure how they are all wired. Also, I'm told that every apartment has a dedicated thermostat that cycles the circulator when (and IF) the apartment reaches temperature.

Please share ideas, suggestions or comments.
Thanks.

ScottSecor

One more thing, a great philosopher (Dan H) once told me (and about a million other people over the years) was to think like the water inside the pipe. After months of sleepless nights (not really) I think I can now see how this system works.

In my mind, the 4" heating trunks act as an extension of the boiler(s). Almost like a eight hundred foot long boiler (want to call it a low loss header, but I can't go that far). Each tiny circ moves a little bit of the heated water to heat a few rads, gets satisfied and cycles off. Not sure it works or will ever work the way we'd want it to, but I'm stuck with it for now.

lchmb

could you add some kind of outdoor reset to drop the boiler temps when outside temps are above 32? drop the boiler to no lower than 140... wont save a ton but every penny helps..

Charlie from wmass

Mod con boilers have shown great savings in shoulder season use. Also the newer mag separators work wonders on water quality. There are ways to utilize smaller separators to keep the budget down while still getting the majority of the rust out of the system before it hits the boilers.

ScottSecor

Lchmb, with the existing system also providing boiler water to the reverse indirect tanks for dhw, we really couldn't use outdoor reset as we needed close to 180 degree boiler water year round. However, we will certainly suggest an outdoor reset type device of some sort and prevent the cast iron boilers from condensing.

Charlie, we used modcons in almost every commercial hot water system we've installed over the last ten years. However, with this unusual system I'm not certain it makes sense. IF the owner agrees, maybe we'll get to install a hybrid system that consists of three boilers. Two cast iron sectional during heavy demand and one modcon for shoulder seasons. I've been hesitant to specify magnetic separators in the past, but on this job I consider it a requirement. We almost always use Caleffi hydro separators on this type of job which certainly help remove sediment.

ScottSecor

Very brief update. We designed a new heating and domestic hot water system last summer. Owner asked for a local engineer, I offered one, but he was unresponsive. Owner asked his own engineer (from NYC), he was not interested. We've had almost no calls from customer this past heating season, assumed we lost the contract. Stopped by recently, same old system still there, magically producing heat and dhw.

I can only imagine the non-stop complaints and the sky-high energy bills. Maybe this summer things will move forward with yet another phone call to the owner. BTW, we plan on having an an engineer on staff in the next month, maybe this will move things along...

Charlie from wmass

Thanks for the update.

Steamhead

I wouldn't hold my breath. Sounds like this guy just doesn't want to spend the money. Time to move on.

Leonard

Cheap landlord....
Wife used to live in a large apt complex ~ 12 buildings each with ~ 45 units. Each building had it's own boilers. As new tenants moved in and showered at same time in AM her Landlord was never too concerned with complaints of running out of hot shower water.

After a week Tenants learn to adjust shower times so have hot water... Landlord's problem is solved at no cost.

SeanBeans

Yeah, what do they care?

They’ll complain and complain and it will never get fixed. The complainers will move out and new complainers will come in.

Landlord still gets the rent!

The worst is multi-family’s with steam, they just don’t care! And they hire the worst!!

I was at a building with 12-14 apartments and they have auto air vents on every road in the building..

I reccomended changing every vent out with the correct one..NOPE!

We went out 4 times changing vents for whoever complained.. everyone won’t complain so they won’t get changed.. until they leak and make lots of noise! Or clog

Charlie from wmass

I work for many multi unit buildings. Funny they pay me to fix things correctly.

Solid_Fuel_Man

Tenants are funny that way, they want a place to live and expect to have heat and hot water.

I worked in a 7 unit building, which was served with a single 3/4" water main. Somehow that all worked out...

Leonard

Lived in an apt for 8 years. 2 long buildings 40 apts each. Good landlord. Heat was even availbe in middle of summer. Never ran out of DHW or heat, except for at end one COLD WINDLY feburary..... the fiber weather stripping on OLD aluminum windows had turned to dust., and wind was blowing in, place got cool.

Had HOT fin and tube baseboards, so I just placed a window box fan near it and installed a LARGE peice of cardboard to direct air thru the fins. I suddenly had LOTS of heat. Turned baseboard into forced convention.