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Originally Posted by snupytcb

how about a differential bypass valve at the boiler or even a wilo pump?

A differential spring loaded check-valve bypass maybe in a desperate situation but you better be on an I/O control with the sensor on the boiler outlet between the boiler & pump or a strict return limit. Still you're asking that check-valve to know the difference between normal running head and return pressure vs. back-pressure build up. I don't think it can be done effectively.

If you use an electric valve, how would it know how much water to bypass, without stalling the end of the line? I don't see how this can be done without some weird controls and a modulating bypass.

I don't see what the addition of another pump would do for it either?

First off: Check if it's a mono or dual pipe system. Dual pipe simplifies things. Mono, you're asking it to do something it's not designed for.

how about a differential bypass valve at the boiler or even a wilo pump?

Nicely done beenthere.

Inspect carefully. Monoflo tees may not look all that different, maybe just a direction stamp on the outlet side or both. The fact that supply and return are from one pipe gives it away, if you can see both the inlet and outlet.

http://www.bellgossett.com/Press/BG-monoflo.asp

Originally Posted by snupytcb

thats a very good point and something i will look into. you may have just saved me alot of headache. thanks for the heads up.

Your welcome.

learning about possible pit falls before we make them is one of the purposes of this forum.

Originally Posted by beenthere

On a monoflo system.
Some of the water flow is diverted to the rad, and then that water comes back into the pipe again. So the GPM in the pipe is the same through out the system, except for between the monoflo tee's feeding the rad.

So if 30 or 40 stats are closed at the same time, you now increased the head pressure the circ is working against. Decreasing GPM in the system.
The rads at the end may no longer have enough water flow.

What will happen to the system in mild weather when 50% or more of those stats close the valves?

Will the system become noisey?
Will the circ burn out because of not being able to get rid of its heat?

What about when all of the valves close when its 55 or 60° outside.

If its actually a monoflo system, you'll have problems.

400 of those stats is going to add head pressure to the system, and the circ may not be able to maintain GPM against the additional head pressure.

Not trying to talk you out of a good project.
Just trying to keep you from being bitten in the butt.

thats a very good point and something i will look into. you may have just saved me alot of headache. thanks for the heads up.

The ONLY way this would work would be to BYPASS arround both monoflow valves when set temp is achieved, so the flow would be maintained through out the system.
You would either need one bypass flow valve on EACH radiator, or on all of the radiators for each apt.

On a monoflo system.
Some of the water flow is diverted to the rad, and then that water comes back into the pipe again. So the GPM in the pipe is the same through out the system, except for between the monoflo tee's feeding the rad.

So if 30 or 40 stats are closed at the same time, you now increased the head pressure the circ is working against. Decreasing GPM in the system.
The rads at the end may no longer have enough water flow.

What will happen to the system in mild weather when 50% or more of those stats close the valves?

Will the system become noisey?
Will the circ burn out because of not being able to get rid of its heat?

What about when all of the valves close when its 55 or 60° outside.

If its actually a monoflo system, you'll have problems.

400 of those stats is going to add head pressure to the system, and the circ may not be able to maintain GPM against the additional head pressure.

Not trying to talk you out of a good project.
Just trying to keep you from being bitten in the butt.

Originally Posted by beenthere

Before you get them to pay for installing 400 of these valves.
And then have to remove them, and refundall of their money.

Shut the water flow off to 3 or 40 of them for an hour or so.

If it effects the others, then you can't install them.

Something simular was done on a 101 apartment building here. Screwed up the entire system.

do you think it would screw up the whole system being mono flo. i would be putting these on the rad and hooking the pipe to it. i will have them try a ball valve first.

Another choice...

http://na.heating.danfoss.com/Conten...47_SIT209.html

Before you get them to pay for installing 400 of these valves.
And then have to remove them, and refundall of their money.

Shut the water flow off to 3 or 40 of them for an hour or so.

If it effects the others, then you can't install them.

Something simular was done on a 101 apartment building here. Screwed up the entire system.

Originally Posted by beenthere

Do the rads already or did they ever have stats on themthat restrict flow, or are you planning to add these.

these are add on's.

Do the rads already or did they ever have stats on themthat restrict flow, or are you planning to add these.

Originally Posted by beenthere

The how do you keep water flow up.
Since if you restrict water flow through a rad on a monoflo, you restrict water flo on all rads.

I think your asking for something like this.

Honeywell Radiator Thermostat w/Remote Sensor

Do these rads already have stats on them?

i think that will work. i will have to look into it some more. when the room comes to desired temp it needs to shut flow off to the rad so it will stop heating. that looks good but i need to check on the sensing range. thank's for the link.

The how do you keep water flow up.
Since if you restrict water flow through a rad on a monoflo, you restrict water flo on all rads.

I think your asking for something like this.

Honeywell Radiator Thermostat w/Remote Sensor

Do these rads already have stats on them?

Originally Posted by beenthere

Can't use use valves that shut off or reduce flo on a monoflo system.

Are you sure its mono flo.

i don't think i can because it needs to actuate according to room temp not water temp. it is a mono flo system. these should look like the thermostats you would use on panel rads. but have sensor bulb. i know i have seen these but i just can't remember where.

Originally Posted by saylor240

ok, i think i get what your saying now, you have a inline water vavle that control water flow thru 400 radiators? or do you have 400 vavles that shut off each one idvidually as they call in each room? I have seen it done both ways either way they make a control for that, but your not looking for a thermostat your looking for a water valve that opens and closes depending on the room ambiant temp thus stopping the water flow. right? ok where have you looked? there has to be something out there, let me see.....

you got it. thank god , i didn't know how else to discribe it. these are to control 400 radiators individually. i have checked taco. caleffi, granger, oven-trop and a few more. no luck yet.

Can't use use valves that shut off or reduce flo on a monoflo system.

Are you sure its mono flo.

you will need a stat to go with it, depending on the vavle voltage 120, or 24 you may have to get transformer also, but you can make it work.

you need something like this?? http://www.grainger.com/Grainger/items/2E789

ok, i think i get what your saying now, you have a inline water vavle that control water flow thru 400 radiators? or do you have 400 vavles that shut off each one idvidually as they call in each room? I have seen it done both ways either way they make a control for that, but your not looking for a thermostat your looking for a water valve that opens and closes depending on the room ambiant temp thus stopping the water flow. right? ok where have you looked? there has to be something out there, let me see.....