monoflow help?

Timco

Strangest thing. Customer with air / purge problems. Fixed the air issues, installed a Crown Bimini with built in ODR. The rads upstairs would not heat even though this is pumped. Found that by removing outdoor sensor and getting heat above 150* I got fine heat upstairs. One loop is true monoflow fitting with a standard return. Other loop is large bell directional fittings that both supply & return connect to. Pumps on returns, of course. Could it be that these loops do not want the pump on the return (sucking) and need the head of either 150*+heat or pump on supply? All rads hot now with water temp over 150. Got flow to two rads with 138* water temp, the ODR target temp for my weather currently.



Tim

bob_46

Mono

Do any of the radiators have valves on them? Have any of the radiators been removed and the runs to them capped?

gerry_6

I'm just thinking

when i saw this job i wondered if it was originally a gravity flow system  because of the large supply and return pipes and if the conversion to pumps was done correct i imagine you would have to manually  vent every single radiator .  Did you put a  ball valve in above the pumps ? wonder if the pumps impeller  are plugged up   after stirring things up.

I'm so sorry if I set you up for a nightmare job .

Sometimes when you start correcting install issues other problems become more apperant.     Gerry Alder

Timco

valves

all have valves, one is piped in backwards. One has a valve on each side to "allow for bleeding". Previous guy put a size bigger than the 15-58 on and charged and said it would heat up in a few hours, and it never did. I can see one set of abandoned pipes in the basement is all, and most of the house is original but obviously there had to be rads in brekfast area and kitchen where there are now toe kick & copper fin. Interesting that 150*+ water made it convect, and turned on the gravity.



Tim

Timco

job

Not at all! She is sooooooo pleased that all rads are hot and the house is warm. I am just curious as to why having pumps on returns would not run monoflow setup. The hotter water made it fly, and the finned BB is really working well now. Purge stations on all returns now. She is really pleased to not have to take up the floors and 'fix the failed fitting under the floor' that she was told was the problem. I just like to have these things figured out.  Thanks for the referral!



Tim

Empire_2

Hey Timco?

It's about bed time and sorry is this sounds funny, but considering monoflo is not my immediate concern.  I was thinking more along the lines of lac of flow.  Take the pump you currently have, look at it on a pump curve....... Will the flow be reasonable since your pipe increased in size?  (I'm looking at velocity here).  Delta "P" regardless of where the pump is.



I don't know maybe I'm tired..... Merry Christmas Timmy



Mike T.

The Steam Whisperer (Formerly Boilerpro)

2nd floor

A couple of things.  With the system at 150F the pressure is higher.  Monoflow fittings produce thier water flow by creating suction on the returns.  A pump installed on the return reduces pressure in the system.  A high pressure drop loop like monoflow cant drop the pressure at the pump inlet dramatically. Combining all these throughts together, I bet the pressure at the pump inlet is dropping below the minimum and the pump capacity is dropping.  Pressure at the top floor may be dropping below atmospheric. 

Monflows really work much better pumping away from the boiler, pressure reducing valve and compression tank. 



Boilerpro

heatguy

monoflo tees

if you are not using a monoflo tee you should remove it or pipe the tees as if it was a bypass ,which it will be .A monoflo tee if left in piping will produce quite a bit of  resistence in circuit.

Charlie from wmass

One more note that may save a call

That kick space heater make sure it has the low temp thermostat to kick in the blower. As said above bypass that dead set of tees. you could use it as an air scoop.

Unknown

I`m with boilerpro,, to a point,,,,,

M/F tees do not create suction,,,they simply provide resistance to the circulated-circuit(main) to allow this heated water to by-pass into the rads.



The higher "push" given from the circ,,, the higher the bypass(into the rads) will be.

Big Ed_4

Gravity but no Flow

Sounds like all your getting is gravity feed heating but no flow .... I seen this problem just last week on a pumping away set up , A G115 with a S150 indirect.... The problem was pipe dope ...Too much of in the system.. Drove me batty.. The installer like to paint the inside of the female threads , I would guess ..Really not needed and against code in my city.. Any way the sticky goo ,I think it was Pro Dope .. I like to use these days ....... , I thought it was a air problem , which it was loaded with air .. Pumping away with a expensive Honeywell air scoop , system loaded with air after the home owner fussed with it all day.. Purged back and forth ... Why is it not auto ? Pulled apart the air scoop to clean the plugged air vent.. Ok thought I solved the problem ... Sitting there after a good purge circulators spinning but no flow ????? Hear a Ca-Cling coming from the indirect flow valve (tank already satisfied )and the flow raced up the pipes.. Why ?? Could a open non restrictive loop delete my pressure drop ??

Timco

confidence

I am very confident that the pump being on the return is robbing my pressure from the top floor and just sending the water into & through the boiler, and from there there's no way to tell it to go back to the top, and it goes out in easier routes to other zones, especially with an abandoned monoflow ftg just 10' from the boiler, first fitting in line on the ceiling. Move pump, bypass mono fitting will be next. A 10-42 was installed to 'get more flow' but because it is on the return, it is just making things worse.



Tim