Monoflo and Circulator

Jonn2018

Hi all, have this monoflo setup 50's house. Has a main line and which close to the boiler breaks into two 1" loops, one goes around the right side the other left side of basement then come back together down the middle of the basement and merge into a 1 1/4" line that goes back into the boiler. So I had borrowed an ultrasonic flow meter, you basically attach the transducers to the main pipe and it measure GPM. I have a Grundfos 15-58 3 speed on the system. What the Utrasonic flow meter shows me at pump speed position no. 2 is about 13-13.40 GPM. So at that rate head is at about a 1ft. Even if I bump it up to pump speed position no. 3 the data sheet shows a pump head of just about 5ft.

So, I think for a monoflo system this is a way wrong pump. Any suggestions? Comments would be appreciated.

Brewbeer

How does it heat? Evenly?

Jonn2018

seems 2nd floor is getting warm but is cooler than first floor

Ironman

You've left a major factor out of the equation: what's the btu output of the boiler? Or better yet, what's the EDR of the connected radiation? We need to know how many btus are being pumped.

EBEBRATT-Ed

What @Ironman said + I have never seen an ultrasonic flow meter that was accurate

Jonn2018

The boiler name plate is:
DOE Heating Capacity  108000 BTU
Net I=B=R Capacity  94000 BTU

A heat load calculation was done for the house and it is: 97778 btu

The convectors in the house from the manufacturer literature will put out 86926.50 @ 20 degree delta tee and 180 temperature.

Zman

Next time you have the flow meter, put it on your water main near the meter and compare the results to what the water meter is showing you. My experience is +/- 30%.

I would agree that the 15-58 is not a great selection for your application. Something high flow and low head would make more sense. How are your supply and return temps?

hot_rod

This B&G Vario has a nice flat curve and a lot of adjustability.
https://s3.amazonaws.com/pumpproducts/pdf/193175_1_B&G+6050B2001+Brochure.pdf

Ironman

13 gpm for a boiler that has a 108k output is a little high, but not that much. Putting it on the lowest speed would probably get you close to 10 - 11 gpm, which it where it should be.

I don't see the problem.

Jonn2018

Zman I'd bet you are right. You know these ultrasonic meters...nice concept in a lab were everything is know. But placement of the transducer heads matters and changes readings, even a slight turn the orientation of the heads across from each other on the pipe. So, I'm with you.

I do have a 1" B&G Thermoflo Balancer. This has a sight glass and it only shows up to 10 GPM on the glass. Plus it's only 1" , The The two 1" lines are horizontal and then merge to a wye that is 1" x 1 1/4" so my vertical lines are 1 1/4", not sure if this thermoflo balancer can be mounted horizontally, even so it's limited to only showing 10GPM.

How about installing gauges on each side of the pump??

Here are a couple pics.

Jonn2018

HOT ROD thanks...yeah I was looking at that suggestion interesting.

IRONMAN I can get the flow down to 10ish by adjusting the speed, but the head is terrible. This system has about 10-11 monoflo tees in it.

Zman

I may stand corrected on this. If you are having trouble getting even flow in a monoflow system, increasing flow would be a good idea. I think more like 20 GPM
https://s3.amazonaws.com/s3.supplyhouse.com/product_files/52722330-submittal.pdf

Jonn2018

How and where would you guys install balance valves on this system?

Ironman

Where is the pump located on the system and how do you know what the head is?

Jonn2018

Hi Bob,
Pump is on the supply side. If my ultrasonic meter is saying the pump is moving say 10 GPM (depending on the speed. Speed no. 3 gives me about 13 GPM) if I look at the pump chart it at least tells me what the max head the pump will give at 10 GPM. I'm not saying the head might not be less than the chart but it can't be more than what the chart says at 10 GPM

hot_rod

I assume there are no TRVs on any of the heat emitters?

What is the goal to get more output upstairs?

It is a fairly complex calculation to determine the resistance in a system like that, every branch and all the connecting piping would need to be calculated. If you can even see all the piping and fittings?
That develops a system curve, which could be overlayed on a pump curves to select the best circulator and define the OP operating point.
Chapter 11 of Modern hydronic Heating takes you through the steps.

Or the trial and error method.

Jonn2018

Correct no TRV. And yes correct on upstairs output. It could be that the system is what it is, however given the readings from the ultrasonic meter, and see that the 15-58 only produces 5 ft head on speed no. 2 and on speed no. 3 - 10 ft head at 10 gpm, I was searching to see is ten feet head even enough. A lot of the pipe I do have access to seeing and measuring.

So I think you are saying find first my total equivalent length of pipe?? I'm wondering if attaching a thermocouple on supply and return lines of the boiler to see delta T would that really tell me anything relavent

hot_rod

But if you are moving 10 gpm, and that flow rate and temperature drop matches the load, what difference does the head make?
Sounds like you need some balance not more pump?

Any changes in the piping, adding or eliminating heat emitters really messes with the original design and layout. If one was ever performed

Decrease then load upstairs? Add some window coverings or any other step to lower the load close to what the emitters provide.

Cover part of the lower emitters if that overshoots the t-stat setting while the upstairs is behind.

Jonn2018

I think I need to see what the temp drop is, I'll get those numbers and see what it looks like. Other than trying to put a balance valve on each heat emitter, how could you balance this system? The system when it splits in the basement left and right has first floor and second floor emitters on it. First and second floors and not separate on this system.

I'm curious on these monoflos if you don't have enough head would you not get some gpm going to the 2nd floor emitter, but struggle to get the full amount?

The only changes in piping I did was there was a basement radiator that i disconnected, but I tied the 2 monoflos tees back together with 1/2" pipe. I did not just cap them.

The First floor Heat Loss calc. tells me I need 51095 btu. The emitters show they can produce 46000Btu.

The second floor Heat Loss calc. tells me I need 48679 btu. The emitters show they can produce 41000Btu.

Would covering the downstairs emitters if the house is on one Tstat, tell us anything?

What about checking temps with a thermocouple meter at the in and out of the second floor emitters, in theory on a monoflo shouldn't at least the in temp be the same for all emitters regardless of what floor they are on?

Ironman

John, I don't quite understand why you're hung up on head. When designing a system, we're concerned about it so that we can size the piping and circulator correctly to get the needed GPM. If you know how many gpm you're moving, the head is a moot point. It's the GPM that's moving the btus; the head it's simply the resistance to that. So again, if you have the gpm, the head is irrelevant.

It's appears that you believe that forcing the system to have more head would increase the flow. The only way that would be true is if you increased the gpm. Again, that's the relevant number. Btus = (gpm X 500) x delta T. Nothing about head in that formula.

If you're having problems getting sufficient heat in certain areas, then may I second what hot rod has suggested.

Also, are you certain that those areas aren't air bound? Monoflo systems can be extremely difficult to purge of air.

Jonn2018

Yes, I guess that is the case. I'm going to purge everything and see what happens. Also try and cover some of the emitter as Hot Rd suggested.

Out of curiosity, how would you add balance valves to this?

hot_rod

Probably more that you want to get involved in, but TRVs on all the heat emitters is the best way to balance, and have individual temperature adjustment and possibly lower the energy bills.

An explanation I heard at a pump manufacturers seminar years ago...

head is the resistance to flow that all the piping , emitters, boilers, devices presents.

Circulators are sized overcome that resistance.

So I suppose circulators don't technically "add head" to the system, they provide the mechanical energy to overcome that resistance or "head".

Solid_Fuel_Man

I was always under the impression that if one wanted to add TRV's to a monoflo, they would need to be 3 way, so as not to add significant restrictions if many rads were not calling. Basically bypassing the radiation when not calling.

hot_rod

Solid_Fuel_Man said:

I was always under the impression that if one wanted to add TRV's to a monoflo, they would need to be 3 way, so as not to add significant restrictions if many rads were not calling. Basically bypassing the radiation when not calling.

Wonder how a ∆P circulator would work? There are schematics in Modern Hydronics showing TRVs on each rad, or a group of rads in one room on a single TRV.

Manual globe valves on each radiator could also adjust.

Solid_Fuel_Man

Even on a monoflo? Isn't it a big no no to cap off an unused branch? A TRV would do the same thing right?

Jonn2018

these are convectors though

Solid_Fuel_Man

I grew up in a monoflo heated house with all iron pipe and convectors. I recall each convector having a sheetmetal flap connected via a linkage a knob on the front to throttle heat output w/o slowing down water flow.

lchmb

I would agree with solid fuel, dont add TRV's unless they have a bypass in them. I've always had good luck using a 008 on monoflo systems myself. My Dad's house was set up 3 floors.. basement was a bit cooler but everything else stayed nice and even...

Solid_Fuel_Man

My parents place had B&G 3 piece circulators. Those were replaced in 1996 with 0010's and those are still in service. 2 zones, downstairs and upstairs. House has 7 convectors per floor if I remember correctly.

Jonn2018

Hot Rod came across your Live - Balance valve video...that was good stuff gave me better understanding of those valves.

So all, in a monoflo system I should be seeing the same temperature at all the convector inlets...regardless if it's first floor or second floor...correct???

Solid_Fuel_Man

No, the first convector will have the hottest supply. The second has mostly boiler temp, but is slightly diluted by the return water from the first convector, and so on.

So a monoflo system is a hybrid between a series loop and a supply/return two pipe strategy.

hot_rod

A brief look at diverter tee systems

EBEBRATT-Ed

@Jon2018

I think your getting hung up on what the ultrasonic is telling you. Those are not accurate. They will lie to you and your goig down the wrong path

Solid_Fuel_Man

I agree with @EBEBRATT-Ed what are your actual supply and return temps on the loop?