Circulator head

Kirkhj

Is there a telltale sign if my circulator does not have enough head? Cast iron boiler. Cast iron rads. I don't know how long it should take to bring the temp up in the house by 1 degree Fahrenheit when water is at 80 
Degrees Fahrenheit on boiler start up. Delta t is never more than 30 or less than about 20

EBEBRATT-Ed

If your delta T is 20 when the system has stabilized you have enough flow. If your over 20 flow is low.

But you have to give it some time to stabilize if from a cold start.

Perhaps you are doing too much setback. I wouldn't go more than 4-5 degrees

Kirkhj

Thanks.
I've learned about the setback and never go more than 2 or 3 degrees. On a start up with the supply temp at around 80 degrees (pilot keeps it pretty warm) I'll get a delta of 30+ I've set the circulator to turn on at 125. The supply temp will reach about 150 before the circulator, which is on the return side, comes on. Then supply temp drops quite fast. Down to about 90 in just a few minutes, but it doesn't move up the supply pipe very fast.
 Once the main floor rads start hitting around 130, which will take at least an hour, the delta starts to stabilize at 20. Second floor will take 1.5 hours.
I just don't have anything to compare it to and don't know if that is normal or slow!

I have an HTP MC 99 I picked up for a song and plan to run it through an indirect and through a flat plate hx, to keep the now 117 year old system isolated from the new boiler. The old 1974 weil boiler could then be a backup, and even though this HTP is barely used there is no guarantee that it will work. If it doesn't I'll still have heat and dhw(electric tank that's gonna go once the mod con is in place and actually working)  

EdTheHeaterMan

It sounds like you have and old system that was designed for constant hand fired boiler and gravity flow of the heat through very large old iron pipes. When installing a new boiler on these old systems, it is important to consider the fact that oil heat and gas heat cycle off and on by thermostats in the living space. The old original hand fired boiler did not turn on and off by a thermostat and did not have circulator pumps.

That said, you do not need a very powerful pump to move the water thru the system, you just need that temperature difference. and that will take some time to make that temperature difference to happen. What is more important is the way the replacement boiler is installed. The cast iron boiler should be installed with a bypass in the near boiler piping in order to provide hot return temperature to reduce flue gas condensation caused by return water temperature lower than 130°F. The new ModCon boilers on the other hand are most efficient with low temperature return water. Just be sure you follow the manufacturers' piping instructions when replacing a boiler with minimal water content attached to an old gravity design system.

Kirkhj

Thanks Ed and yes the old coal fired tombstone shaped boiler still sits in the basement. There is about 500' of 1.25 and 1" black running through the whole house. 
When I moved in 6 years ago the chimney liner was rotten. I thought  that was because the high limit on the boiler was set to 140. Now that I know it's the return water temp that dictates, I should have a look at that liner and get that thermostatic bypass on right away before doing anything else!

Since I have to tap into the return and supply pipe, it it worth moving that circulator to the supply side?

Thanks again Ed!

mattmia2

It is worth moving the circulator and getting the expansion tank and air removal in the right place, here's why:
https://heatinghelp.com/systems-help-center/pumping-away-piping/

This assumes you have a diaphragm type expansion tank. If you have a conventional compression tank hung from the ceiling then your strategy needs to be somewhat different.

Kirkhj

I actually read the book pumping away some time ago. Guess I should read it again!

Kirkhj

I actually.read the book pumping away a few years back. Guess I should read it again!
Air in this system without any form of air scoop is almost completely non existent. I checked all the rads before the heating season started this year. No air whatsoever and from.what I recall there was none last year either. I have one autovent one just one rad on the main floor.  Should I still add an air scoop even though there is no evidence of air in the system?

mattmia2

I would use a microbubble reabsorber type of air eliminator. There will be air introduced whenever you add fresh water to the system because the water has air dissolved in it. The more air you get out, the less oxygen there is to corrode parts of the system. I would clean up whatever is going on with the multiple expansion tanks and get them on the suction side of the circulator and add some isolation valve so you can take the pressure off to charge them or replace them without draining the system(there should be both an isolation valve and a drain after the isolation valve)

neilc

that picture with the expansion tanks,
is the ball valve to the left of the tanks closed?
still ?
needs to be open

Kirkhj

Microbubble reabsorber? That's a new one to me. I'll have to look that up. I never considered an air scoop of any kind simply because I didn't think it would do anything. At one  time I had the fill valve shut off for several of the heating months and on checking bleeders there was no air evident, but now I understand that just checking if there is air at the bleeders while the autofill is open will introduce oxygen, so I'll put that microbubble reabsorber on, once I find out what it is. Lol

There are 2 expansion tanks because when I moved here there was one in a different spot and it was completely shot, so I put a new one in the present location, because it was the easiest place to add a line. That one was too small, so I added a second one and yes there is an isolater at both ends of the tanks plus a capped drain.

The supply ball valve to the expansion tanks is open.
Before the beginning of every heating season, I remove and check/adjust the pressure of the tanks to match the static pressure. It's been working like this for about 4 years now.

Kirkhj

Thanks neilc. That ball valve to the tanks was closed when I took that pic. Good eye! 

Kirkhj

Ed the heater man.
Right now what I would like to accomplish first and foremost is to get that newer boiler in place and set up while.doing as little as possible to the existing system because it works and I am time and budget limited.
Using that new to me HTP, which I have no guarantee will actually function, as a primary circuit with a flat plate hx to transfer heat to the existing system is just theory to me. I can do the gruntwork, I've already done a fair amount to the old pipes but I want to be sure I still have heat while that new boiler circuit is being installed, which means I will likely have to do some things twice. That's OK. Its just my own time!

EdTheHeaterMan

I am wondering if you can be more specific on the actual model number and size of the HTP boiler you are talking about





As you can see from these illustrations there are several to choose from in 2021 alone, there may also be discontinued models that are not listed herein

If by chance you have one of the boilers designed for potable water heating, I would not recommend using that as a space heating appliance. Some DYI persons have tried and end up on this site trying to get some answers on why it does not work the way they think it should. That is because it is designed to work on an open system at higher water pressures and flow rates than your typical space heating closed system.

I could offer you some suggested piping designs, only if I know what equipment I am actually dealing with.

Picture of Model and Serial number name plate (sticker) affixed to the appliance will help.

EdTheHeaterMan

Assuming that you have a Space Heating ModCon from HTP, I might suggest this piping configuration. First is the existing Weil McLain piping as it is existing in your basement. (ignoring the gray out area and concentrating on the solid lines as your 1-1/2" iron pipe.)

This is what I would suggest for keeping the Weil Mclain boiler and adding the HTP Boiler.

I realize this is much more piping than you had in mind, but if you want to do it right, this is the right way to do it. You can make the existing Weil Mclain boiler the secondary boiler with a manual switch or you can have an automatic switch based on outdoor temperature.

Or you could just do this.
with some valves placed in the proper places so the heated water does not go where it ain't supposed to. (Like heating the boiler that is not in use)

EBEBRATT-Ed

Return line to the HTP is on the wrong side of the Weil Mclain pump in the last drawing.

EdTheHeaterMan

EBEBRATT-Ed said:

Return line to the HTP is on the wrong side of the Weil Mclain pump in the last drawing.

I'm not saying that I would do it this way, Ed, That last picture is kind of sarcastic and kind of what I expect the OP might do anyway. And I'm a little insulted by your comment, Do you know how much I had to pay the Art Department for that high tech illustration? Some people have no sense of humor!

(really not insulted Ed LOL)

It all depends where you place the valves. And they should be full port 1" on a 75,000 BTU heater or 1-1/4" on the Larger heaters. When you think about how the water will flow thru the WM boiler without some valves on the existing iron pipes to isolate the WM boiler, the OP will have some heat going up the vent pipe as the HTP heats up the Weil McLain. Water taking the path of least resistance and all... and most DYIs don't realise that they need to put arrows on the inside of the pipe so the water knows which way to go.

Kirkhj

You really hit the nail on the head with this one Ed. Looks like you really understand what I"m trying to achieve. 
I have an HTP 99 MC with a 2014 manufacturing date. According to the pics of it I saw, it was fully  installed, but never hooked up to a supply. It was purchased in 2016 and just hung there on the wall complete with near boiler piping and 2 ×15-58's...

The flat plate idea came from a fellow who designs boiler boards and as much as I did like the idea I was just a bit concerned about using that HTP for such a tiny circuit, hence my first question about the pump head etc! I also had some worries about changing the ph. This 117 year old system has a ph of 8 and I was more concerned about changing that because I was worried more about it hurting the rads. I guess that's partly why the flat ate was suggested.

That piping is not more than I envisioned and I think that first drawing, (even though the second one is so much prettier, lol) is a much better idea for several reasons. 
The circ on the return side of the weil can stay right where it is, I won't need a flat plate, and I can hang that HTP and run almost everything else with very minimal dissasembly,heat down time etc,  then have the gas fitter come in and do his thing. Exactly what I want. 

I've also read a few of Dan Holohans works, so I somewhat understand the primary secondary setup. What I really appreciate is the simplicity and the fact that it just works, when done properly of course.

I've created a wall space by moving my HWT so I now have a good 8'x7' of wall for a board and piping etc. plus a perfect spot for intake/exhaust to boot. 

That being said I have a couple of questions, if you don't mind.

The hwt right now is electric. ( it was there when I moved in) I would like to add tees, isolators etc for when I get an indirect.
Where would you suggest I put those?

Is that backflow or check valve on the return to the weil before the circulator the only one necessary?

Is a thermal bypass for the cast boiler unnecessary with this configuration? I don't have one now, but now would also be the time to add one I would think!

I'm not even sure if this is a modulating or a 2 stage boiler. I don't see a turndown ratio in the manual but do see a min and max input. 44k and 99k. 

Btw I decided to paint arrows on the outside of the pipes. I didnt want to take a chance on contaminating that new boiler by running paint chips through it. Did I pass? Lol

Kirkhj

Hmm. The manual does show it as a space heating device, but this pic tells me it's one of those potable water only boilers. Everything read in the manual shows  that its just another modcon with dhw priority etc. With a stainless hx. Allowable ph 6-8. 

Kirkhj

EdTheHeaterMan

I like when my humor is appreciated by the Non-Pro LOL You Passed!

Piping for indirect is to follow.

EdTheHeaterMan

This is the manual for your HTP
https://htproducts.com/literature/lp-171.pdf

On page 27 is this piping diagram


I have modified it to more closely match what i believe is your system. (except for the baseboard loop... that is to be viewed as your cast iron radiators and iron pipe to the original WM boiler.)

Now you must use 3 circulators. Look carefully, the main or Primary Loop is the one with the expansion tank (incorrectly labeled by HTP in my previous post) The supply and return are removed from the weil mclain and connected to each other with the circulator, microbubble air vent, expansion tank and fill valve system, forming a loop that just pumps cold water from the return to the supply.

Somewhere in the primary loop just before the microbubble air vent you place 2 closely spaced tees to connect the boiler so heated water can be injected into the primary loop.

If you compare the diagram from my earlier post (before the model number) to this diagram in this post, you will see that they are very similar. But I like the look of the first diagram where the boilers are attached to the incorrectly labeled Primary loop. (Secondary should say Primary)

Kirkhj

Non pro, but being a non ticketed maintenance guy I've worked with many electricians, hvac techs and plumbers. Dead meat if one cannot relate! Lol

Yes the first drawing is easier to understand and it seems to be more simplified. Yes that is the same manual I printed out and put in a 3 ring binder on single side printed only paper. I didnt catch that mistake with that incorrectly labeled primary circuit though! 

I need 18 horizontal inches of pipe before the Spiro if I remember right?

So with this new configuration I could run both or choose which boiler I decide to run? Although you did say it would be just a cold water pump, it appears that way to me. Remember, I still need this weil until I know for sure the HTP is good to go and also have that back up!

EdTheHeaterMan

You do not need 18" for a spirovent Jr. you need 18 inches of approach piping for this air scoop



You can use a short nipple and connect to an elbow or Tee fitting within a few inches. The air separation in a microbubble air vent does not depend on "laminar flow" for efficient air removal.

EdTheHeaterMan

I want to be perfectly clear so I have taken this piping diagram from a different HTP manual to illustrate what I mean by circulating cold water in the primary loop. (the diagram from before I had your model number)




The blue line indicates the primary loop and how it will just circulate cold water if no boiler is connected. (as in valves closed). The red and orange lines indicate the heat being added by your Weil McLain until the HTP is operational. You need to see how the Weil Mclain has a complete repipe in the boiler room in order to accommodate two boilers connected to one primary system loop.

Sometimes I get a bad vibe from your reply comments indicating that I may not have been as clear as I should be. As a Pro, I sometimes think that what is in my mind is crystal clear when my words are actually as clear as mud.

I"m sorry if I'm being redundant.

EdTheHeaterMan

overkill redundancy squaired

That little white section of the diagram will be in the 8' x 7' section of basement wall you have reserved for the repipe. and hanging the HTP. The WM can stay where it is and just use some copper to connect it.

Look at the Zoning Made Easy booklet for necessary pipe size for your connection pipe and shared pipe

here is the link for that booklet
http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf

Kirkhj

I completely understand what you mean by having a clear picture in your head. As a supervisor I often told people," If you don't understand what I am telling you, ask me as many times as is necessary until we both know you understand. The picture in my head is very easy for me to understand, but that doesn't mean that you do"

Thanks Ed. I really do appreciate your help and understanding. Impressed and also fascinated at how fast you altered those diagrams and explanations. I wouldn't have a clue...

BTW here is the actual spot I cleared.  

Kirkhj

Kirkhj

Wow. I just had a closer look at the diagram explaining where the close spaced tees can go. That really simplifies things for me. I never would have figured out they could go right there. 
Very much appreciated Ed.

Kirkhj

So my idea now is to take out that boarded up old window, insulate and drill holes for intake/exhaust then put an insulated wall up for the new install, but I'm not sure what kind on insulation, if any, would be safe to use behind that htp.

Also, does it matter if the close spaced tees are vertical? I cant imagine it would matter, but it doesn't hurt to ask!
The length of supply pipe running ro the homemade 'manifold' is only 2' from that first elbow right above the boiler outlet. The only place I can tap in right now is in that short length of pipe. The rest of the supply/return beyond that point is a 
job for the end of the heating system. Almost every single pipe and fitting are threaded right up to the rads with no unions, except for the few upstream I've added. It must have been brutal to thread pipe in 1904, or unions just simply did not exist yet!