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Will Series-100 push water farther than NRF-22?

(Reposting as a new thread).

I recently noticed that the baseboard radiator on the 3rd floor of my house is stone cold.

We have not used this room since before Christmas, when the radiator was working fine.

On Christmas Day, I swapped out my Series-100 with an NRF-22 which was the start of a previous post of mine. That is the only change I have made to the system.

So does the NRF-22 not have enough head to push water to this radiator?

It is the furthest one from the boiler (located in the basement).

The other radiator on the third floor is a large free-standing one and it heats up fine.

The two third floor radiators are on the same zone as the second floor radiators, but there are two sets of pipes to these 3rd floor radiators.

The warm 3rd floor radiator is served by pipes that branch to two other radiators on the second floor (both have TRVs turned all the way down).

The cold 3rd floor radiator is served by different pipes that branch to three other radiators on the second floor (two on full blast, one limited by a TRV but not turned down).

I have ordered a replacement coupler for my Series-100 and will swap it back in to see if that solves this problem.

Eric Peterson


  • Paul SPaul S Member Posts: 1,228

    I don't know what you have in btus, GPM, type of system etc. .... But here's an example 100 series @ 5ft hd =23Gpm .... nrf-22 @ 5ft hd= 14gpm.... so yes 100 series moves more water.....Paul S
    ASM Mechanical Company
    Located in Staten Island NY
    Servicing all 5 boroughs of NYC.
    [email protected]
  • EricPetersonEricPeterson Member Posts: 32
    More GPM, yes but

    my question is about distance. I would expect a lower flow rate with the NRF-22, but thought it would still pump water through all the radiators.

    That does not seem to be the case.

    Perhaps there is just enough resistance to get to the third floor and the NRF-22 can't push the water up there?
  • Harvey RamerHarvey Ramer Member Posts: 1,929
    What is your system

    pressure at the boiler? Have you tried bleeding air out of the radiator?

    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • EricPetersonEricPeterson Member Posts: 32
    System Pressure

    is 14 at the boiler. There are two bleed valves on the baseboard and no air in either one.
  • Harvey RamerHarvey Ramer Member Posts: 1,929
    Your system pressure

    Is marginal. If your circulator is on the return pipe and pumping toward the expansion tank it is to low.

    I was having a little difficulty following your description of the pipes. If you would humor us and draw a diagram of your system layout and post it, that would help a lot.

    Also your description of stone cold is exactly that, not Luke warm?

    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • EricPetersonEricPeterson Member Posts: 32
    Well this is embarassing!

    To answer your question, I went to check the piping in the basement and found a surprise.

    There are ball shutoff valves on all the pipes, which made it easy to replace the pump on 12/25 after shutting them all off.

    Then I opened them all.

    Except one.

    The one to the stone cold radiator.

    And yes it is, or was, stone cold.

    But thanks to your question, the problem has been solved!
  • Harvey RamerHarvey Ramer Member Posts: 1,929
    Ha ha

    A closed ball valve will do every time ;-)


    Ramer Mechanical
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • icesailoricesailor Member Posts: 7,265

    Hydronic heating circulators don't push water up to heights. If there isn't enough pressure in a heating system to raise the water to the top of the system with room to spare, if doesn't matter how big a circulator you have, it isn't going to circulate water.

    1# PSI Gauge of water pressure will support a column of water 2.31' high. If you take a 1" glass pipe and a 24" glass pipe 100' high and pump water in it where a pressure gauge is located at the bottom, and it reads 12# PSI Gauge, the water level in both pipes will be about 27' 9" high. IN BOTH PIPES. The only difference is that the water in the 1" pipe weighs less than the water in the 24" pipe. The weight of the water has absolutely no bearing on the issue.

    If you take a coil of 1" poly pipe and make it into a 100' in diameter circle and flop it horizontally on the ground, connect a circulator to the two ends and put a pressure gauge on both ends and turn it on, the water will run merrily around. If you connect a expansion tank and a 12# fill valve to the system at the circulator, both gauges will read 12# PSI Gauge at rest. If you turn on the pump (while the circular piping is horizontal), the pressure on the discharge might rise to 15# PSI Gauge and the return going into the might be 9# PSI Gauge. Therefore, the pump needs to develop enough energy to overcome 6# PSI Gauge or 13.86' of HEAD pressure. It is also the resistance of the piping for the pump to push against. It doesn't matter where you put the pump in the loop, it stays the same. As long as the pipe is completely full of water and has no air in it. It just circulates the water around and around.

    If you take the 100' diameter circular pipe assembly and turn it to the vertical, the pressure in the pipe will need to be raised to 43.4# PSI Gauge so that the water in the circle is equal all the to the top.  The pressure gauges at the bottom where the pump is will both read 43.4# PSI Gauge. We'll round it off to 44# PSIG. When you start the pump, the outlet will read 47# PSIG and the return will read 41# PSIG. Because of the 6# PSIG resistance of the piping. It doesn't change because of the horizontal shift to the vertical. Just like the wheel of a truck or a ferris wheel.

    If the pressure that worked at 12# PSIG when the circular pipe wheel is left at 12# and turned to the vertical, the water will flow as long as there is no air able to get in above a water level of 27' 9" or 28'. But above 28', the upper water pressure is negative and will draw any gasses out of the fluid water. The circulator pump can't develop enough pressure to move the air around the pipe.

    Putting a bigger pump is only going to waste money and energy when all that is needed is more pressure in the system.

    If you live in a city or town that has municipal water and they have a water  tower, and you put a pressure gauge at any place in the system, or your house, and say the pressure reads 65# PSIG, the water level in the water tower is 150' above the gauge.

    Those old gravity expansion tanks they had in top floor closets on open gravity systems where they had a gauge glass on the side and an overflow pipe from the top of the tank to the basement, when you overfilled the system, it ran out the overflow and all over you.

    If you go to try to get heat flowing into a cold upper floor radiator, and you open the bleeder and get little air for  moment then it stops, you need more pressure in the boiler. You need to set the pressure higher. It may also be time to replace a broken fill valve. Replace it with one with a fast fill feature like a Watts 1156F. "F" stands for Fast Fill.

    Bigger circulators have absolutely no effect on how high the water pumps into a system. Only the amount of resistance, measured in "foot of head" that it will develop to overcome resistance in the piping, The other part is how much fluid it will push at a given pressure against system resistance.

  • EricPetersonEricPeterson Member Posts: 32
    Got it - but that was my confusion

    because while I know that circulators don't push water, and the only effect of the NRF-22 should have been lower head, thus longer time for the water to circulate, meaning greater delta-T, still I had this cold radiator!

    I should have checked all the shut-off valves as a first step.

    I do have a fast-fill valve, which is helpful for bleeding air out out the top. When I use this fast fill I just have to hustle back down to the basement to flip the valve back to normal operating position before the pressure builds up too much.

    BTW I am pumping away.

  • icesailoricesailor Member Posts: 7,265
    Pumping Away/ Pumping into:

    Pumping away or pumping into, if you have valves on all the zone returns, and a valve on the final return going into the boiler with a boiler drain above it, there is absolutely no need for you to be trotting your self up and down to do ANYTHING.

    Park your behind in front of the boiler where you can easily reach the fast fill lever and read the system pressure. If you were dumb enough to have piped the boiler feed into the bottom of the boiler (like I was taught to do by my old dead boss) and I always do, when you are purging, it can be into a 5 gallon bucket with a handle. "I" put my massive paw on the zone return. I can feel the lack of warmth. Then, the pipe gets cold. Then it starts to get hot . While spewing air out of the hose. Once it stays hot for the time my experience says is long enough, I open the return valve, shut off the fast fill and keep my hand on the return. If it is working, the pipe will get so hot that you can't keep your hand on it.

    You didn't have enough pressure in the system before you changed the circulator. You didn't need a bigger more expensive one.

    My legs and knees hurt now just thinking about you running up and down three flights of stairs. How's your back, knees and legs holding out?

    If it was working before, and it isn't now, what changed?

    Keep it simple. Always look for the obvious first.
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