Ok guys I've been googling up the wazoo today to try to figure this out.
I have a two zone system, upper and lower. Gas furnace, one pump(Grundfos
Type UP 15-42F), two valves(Honeywell V8048E), and baseboards.
here she is:
I thought I had frozen lines but when I bleed the zones water flows just
fine. So I followed the procedures to purge each zone and started the
system back up.
Well, I still only have heat to PART of the upstairs zone and no heat
downstairs. I'm at a loss what to try next. The thermostats are working,
the solenoids/valves are working, the aquastat is working, all manual valves
are open, PSI is good(15). I can feel the pipes are nice and hot coming out
of the furnace but they go into the concrete so it's hard to trace.
Actually, downstairs there is a little in a baseboard about 4 feet from the
furnace, but that's it. And, to make things even more fun.. the first floor
pipes are in the concrete floor so I can't get to them or trace their exact
route! grrrrrrr. I think this one warm baseboard is the first unit off the
Can it be my pump is dying and can't get the whole system flowing? The
thing is so quiet I can't tell if it's on or off.. It's a Grundfos Type UP
15-42F, by the way.
What else can I try???
T-- (thank God for gas fireplaces!)
Please reply to group.. I'm trying to remain spam-free.
How do you know the thermostats are working, you say you can't tell if
it's off or on, (since it runs so quiet)
You claim partial heat upstairs, could it be full heat upstairs? and
you are missing the downstairs heat rising?
I saw the picture, what a beast!
I know the thermostats are working because they properly turn on the system.
I've checked and double checked everything with the voltmeter as well.
I couldn't tell if the pump was working, or that's what I meant by the
no full heat upstairs.. It's hard to explain but each zone has two physical
loops. The upstairs: About 3 feet from the furnace it splits at a T to
these two loops to the upstairs. Then, they return to another T on the
return loop, just before the furnace. One loop heats up perfectly, the
other loop stays cool even though both are fully open... very weird. I
_think_ I eliminated the possibility of blockage, since when purging the
water flows freely.
In the pic you can see the two loops for the downstairs(the taller two going
into the concrete), and the return T just before returning to the furnace.
The downstairs baseboards, also a single zone with two physical loops, stays
cold. But, those two pipes coming out of the furnace, into the floor, are
A beast? I was thinking it was pretty simple.. which is why I can't for the
life of me, figure out the problem! ;)
Yep, got 120 at the pump. My guestimate is that it IS the pump.. but how to
Since the one loop always works fine, it's confusing the sh*t out of me :)
The one loop that does work is located fairly vertically above the furnace,
so I was wondering if it's just the heat rising up and through.. BUT the
return is nice and hot too..
With the solenoid valves open manually the pump may still not be called upon
to start. You may only be feeling heat due to gravity fed convection of
water in the pipes. With both valves open, the pump may not have the
capacity to serve both zones, try closing one valve. Turn the thremostat up
or down to see if you can hear a relay click in the heater or a difference
in the pump noise or vibration.
Sure sounds like the pump is not doing the job. You can check to see if AC
is sent to it and you should still be able to tell if it is running by feel
or by peeking in a vent hole in its case.
Often the pump motor is connected to the pump impeller by a spring and arm
mechanism. It absorbs startup shock when the motor kicks in but if the
springs break, the motor will spin but the pump will be still.
The pump motor and pump (impeller) itself should be considered seperately
when troubleshooting because either can fail independent of the other even
though they look like one unit.
This sounds like the most logical explanation. Especially if it has been
sitting inactive over the summer things like that tend to pop up at startup
BTW, you don't have a furnace, you have a boiler. Furnaces heat air,
boilers heat water. Using the wrong terminology will get nothing but
disrespect if you go to the plumbing supply house for a part.
Well, when I bled each zone, closing its shutoff valve and opening the purge
valve, the water coming out was solid and flowing. I let it run for a
while, and then bled them again. And yes, I had the supply running. :)
maybe we're getting our terms mixed up? I'm actually 'purging', which is
done from the boiler area. There aren't any bleed valves in any of the
radiators of the house.
You close the valve to centralize your purging to the zone you want to work
on. so you're purging one zone at a time..
I always bleed without the supply on, fill to your pressure needed cold
by the gauge and bleed with boiler off then boiler on, the pump working
and a heated boiler will make a difference if its working. It sounds
like the pump or zone valve
alt.hvac added (help us out here pros!)
Hey you guys, that was a lady asking, tell us some more!
I've already read quite a bit of misinformation in this thread,
as I'm having the same problem with my Grundfos 15-42 F.
It's darn cold, and I don't know if the pipes are froze,
or if there is a blockage, or and air lock, or the pump
is just gone. There is no vent hole, I've got no backup
valves, the flow control valves won't turn manually,
some kind of ancient TACO crap, frozen solid.
The upstairs zone is going like gangbusters with
the big B&G pump, but the downstairs Grundfos
zone just quit, no flow, no hot pipes past the flow
control valve, registers dead cold. The pump is running
and I went out and got a little bleeder key, but
where the hell do I start? I want to do it right.
If I have to take the pump out, I'll have to drain
the system, so I may as well put in an air
scoop, backup valves etc, but maybe it could
be something simple, like that air tank.
If one zone is working, do I forget the air tank?
How often do those old check valves freeze up?
I notice there is a plug on the bottom, can I just
remove that and clear it of any crap in there?
Help us out pros!
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