Adding basement radiator seems to stop circulation

capouch

Trying to get my head around this. I have a ca 2006 Burnham Series 2 boiler. Two zones, all cast-iron radiators. One zone is downstairs radiators; the other is up.

On of the upstairs radiators froze up and busted before I got the place, and so that feed (from the pipes which run along the basement ceiling) had been shut off. I remove the part leading to upstairs and instead fed a small cast-iron radiator in the basement. The radiator is below the level of both the boiler feed and return lines, and is being fed from approximately 8 feet overhead.

When I brought it up, what seemed to happen is that circulation was slowed or stopped; the boiler would kick on but the upstairs radiators were just warm, not hot. The basement radiator was plenty hot. One additional small twist is that the new radiator had 1" fittings on it, and instead of buying new, I put in reducer bushings on the 1" fittings to match the 1/2" pipe that was already there.

Google hasn't been much help here. Looking for a technical explanation, and also curious as to whether there is a fix. I suspect that the explanation is related to an adage I've seen" "Circulators are not pumps!!"

Thanks in advance for any advice that may be forthcoming.

(Also this got mis-posted to the Gas Heating sub-list TWICE by mistake. Now I see what I did wrong--how do I delete those posts?)

EBEBRATT-Ed

Post a few pictures of the boiler and the piping around the boiler and the piping to the new radiator and maybe a sketch of how the house is piped

Jamie Hall

Also, if the radiators are fed by Ts off the main line, a picture of at least one of those Ts.

Erin Holohan Haskell

capouch said:

(Also this got mis-posted to the Gas Heating sub-list TWICE by mistake. Now I see what I did wrong--how do I delete those posts?)

I've deleted them. Thanks!

capouch

The boiler is in a "utilities" room, and the hot-water lines are intermingled with potable water lines, gas lines, and even the large-bore piping for the basement-based central vacuum system. My images from that area are pretty undeciperable. But the setup is easy to describe, and I have a few pictures that I think will help.

Two zones; circulators are on the return side. Supply comes up and makes a 3-way split: two pairs (one for each zone) of 3/4" lines make a loop around the basement, and there are pairs of what appear to be straight tees that service each radiator along the way. One other pair of lines on the downstairs zone does the same thing for three radiators on the first floor.

The new radiator was plumbed with 1/2" oxygen barrier PEX. Sits on the floor and both supply and return are about 12-16" from the level of the supply and return outputs of the boiler.

Picture one is the 4-pipe "loop," two is a typical tap, three is the new radiator and four is where it taps into the system, as part of the UPSTAIRS loop. So it's two stories below the other radiators on that zone.

System has worked flawlessly for about 14 months until I added the new radiator, and works flawlessly again now with the supply valve at the radiator turned off. I took pictures at the boiler, but it would take a LOT of words to explain the maze that it depicts.

capouch

This tap is on the upstairs zone; it uses the tee that formerly fed a radiator upstairs that got frozen, so the valves were shut off. So that zone now has four radiators, 3 on the second floor and one in the basement, ergo two floors apart. So that odd split seemed suspicious to me. . .

JUGHNE

Tommay's suggestion may work for you.
If you throttle down those valves for minimal flow more water may go upstairs.

As you see the basement radiator that is connect bottom to bottom I think most of your flow might just shoot across the bottom of that rad and return to the boiler. Robbing flow to the rest of the units.

However how do we know if this is a monoflow system.....there are 2 pipes. Mono implies a single pipe with the tees installed that divert part of the flow off into the tee branch.
This looks like parallel flow piping.

JUGHNE

So we have 2 pipes, assume one supply and one return, each of which have a tee feeding a single radiator.
And that is a monoflow system?

I always thought a monoflow system had 2 tees in the same pipe that has water flow, some of which was diverted away to the emitter and then returned to the same pipe thru the second tee.
I guess I read the book wrong.

JUGHNE

Thank you, new concept, different approach.

capouch

I don't think at any level this is a monoflow system; there are distinct supply and return lines. Circulators are on the return side. I want to understand, this isn't monoflow, right?

JUGHNE

Tommay, do you see any mono flow tees in this system???

Would you have 2 pipes, supply & return, with a tee in each and still call that a monoflow??

IMO, this is a simple parallel piped flow system.

Closest radiation gets the most flow and farthest away get less flow.

The basement rad is the closest and gets most of the flow.

Perhaps others will give an opinion.

FACT: you have been a member for 56 hours and received 5 disagrees, this must be a record.

neilc

so what happened with the idea of throttling the basement valve ?
restrict flow there till ya get flow upstairs

capouch

neilc said:

so what happened with the idea of throttling the basement valve ?
restrict flow there till ya get flow upstairs

I was for certain getting flow upstairs with the new radiator running. All units were warm and I could hear the water passing through them when I first brought up the new radiator.

So I haven't been able to "catch" the precipitating situation in action, but I did try to throttle back that radiator, opening the valve just a crack or two. Thing ran perfectly for the first cycle, and then--stupidly--I went to bed, assuming all would be well.

Woke up to a ZONE ONLY (other zone was working fine) that hadn't had heat since the cycle before I went to bed. In the cases of both failures, the culprit appears to be the relay that fires up the circulator when the call comes from the thermostat. I can't explain it, of course, but I can report that both times, I manually opened up the relay and did the magnet's work for it, pressing on the phenol to close the contacts. It immediately popped back off again, BUT the circulator fired up when I pressed it. So then I pressed it and held it in until the boiler fired and some circulation of the warm water happened. Then I let go. The relay released. Seconds later--both times--the relay closed on its own and all was well.

I'm not very expert but I got this system running and has worked perfectly without the new radiator for 15 months, through several bitter cold snaps. My hypothesis is that the new unit is stressing the circulator somehow and interfering with its operation after some length of time it runs.

The house was built in 1916; the coal boiler was replaced with propane in the late 40s-early 50s; the control system was a brand new set of Thrush components, most of which are still in place. A new boiler was installed ca. 2006.

This circuit now spans a large vertical distance, basically from the bottom of the basement floor to about 5' up on the second floor, and I can't help but think that this distance is a causative or at least contributing factor to the failures that followed bringing up that new radiator.

neilc

whoa, wait a minute,
this is an electrical issue, not a flow issue,
you trip the relay and the circ starts and all is well ?

how many thermostats ?
any new ones? Nest ?
batteries in the thermostats ?

but then you say you heard the water flow also,
so there's air in the system also? like a trickleing brook?

PC7060

Add a TRV to the problem unit, set it for mid range.  This will throttle the unit and reduce the direct flow problem you are seeing. 

I’ve got 19 rads on 3 levels, each with a TRV so I can easily balance the flow based on demand for that area. This is made easier by the large 2” primary lines in my series/parallel system. 

If you have smaller lines in your configuration, the water will take the easier route and significantly reduce flow to remaining branch’s. Exactly like you are describing. 

capouch

@neilc Thermostats are RCS X10 based; I do not believe it's an electrical issue, although I do believe the symptom is showing up as such. Glad to make the case in detail but will hold it for now--the perfect operation of the system before and after spinning up the new radiator being the primary evidence.

No air in system; there is a barely detectable sound that is proportional to the amount of "cracked" I have on the flow valve. Water only at the bleeders throughout the system. Again, system operates perfectly, as it has for a year and a half, as long as the new radiator is out of the system.

capouch

@PC7060 How would the TRV differ from my manually throttling it by only opening the valve a very small fraction? That's what I did on Test #2; it wasn't even half a turn. Still caused the shutdown issue.

mattmia2

Jumper t t or whatever the thermostat terminals in the relay are and see if the relay pulls in. Take some pictures, if it is 1950s thrush controls it might be something weird, but it is a control problem and a balance problem. You might have got some ghost flow or gravity flow from the other zone that the new radiator changed. The circulator issue may have been going on for a while, but figuring out the circulator relay not pulling in is the first step.

mattmia2

@tommay parallel flow and monoflow/diverter tee systems are 2 different system designs. Parallel flow uses a separate supply and return main. Monoflow uses one main with diverter tees that diverts some of the flow in the single main to the emitters. A reverse return system uses separate supply and return mains as well but attempts to connect the emitter that is furthest from the boiler on the supply closest to to the boiler on the return to help balance the system.

neilc

weak voltage or weak relay coil ?
old loose thermostat wiring ?

a sketch of boiler, circs, and thermostats,
or pictures

mattmia2

Read idronics. The flow is throught the emitters from supply main to return main.

JUGHNE

Reverse return has been in engineering piping diagrams for maybe 80 years, at least.

capouch

@mattmia2 It's a pretty vanilla Honeywell RA832, and has been in service for many years, 16 months of that under my watch. Closing the T-T contacts leads to the relay firing 100% of the time EXCEPT FOR two incidents, each of which followed by 1-2 cycles my opening flow to the new radiator. And after the "press to start" trick I learned by trial-and-error (saw that T was closed, and yet relay was open) by manually closing the relay for a short bit, which seems to reset it to proper operation.

That's what led to my assumption that something happening (super-high load on circulator??) downstream somehow that is causing the anomaly. It's cycled a dozen or so times since I "fixed" it after it failed last night following my second spin-up of the new radiator.

I long for an explanation, as I feel within it will lie the solution to my issue.

mattmia2

The only explination I can think of other than a bad control and coincidence is that the lack of flow through the rest of the system means it isnt dumping the heat from the boiler in the system and the aquastat is in the t t circuit and is shutting it off on high limit (or the control is powered through the high limit). If you jumper t t and it doesn't close and the control has power it has to be the control.

PC7060

Have you cleaned and flushed the lines?  Could be you have build up in the old iron pipes that is restricting flow.  No reason the water should not flow readily otherwise. You set up is pretty much same as my old house and the basement radiators get good flow.  What size are the parallel lines which feed the series branches?

capouch

@PC7060 I had to do some flushing as part of the install. Lines are nice and clean, and again--things work perfectly 100% w/o the new radiator.

@mattmia2 My bet is that the relay is firing, starting the circulator, and then at some point subsequent something going on between the relay and the circulator is causing the relay to jump off. Would the relay fire on the 0-1 transition of the thermostat input? If so, there wouldn't be such a thing in that scenario b/c the thermostat's call was never satisfied. We're in the third day of perfect operation now; the only glitches in ~15 months were the two days I had the other radiator in the circuit.

ratio

Relays are level triggered, not edge triggered. I've seen relays that wouldn't pull in but stayed in once manually engaged. Most of the time it was a wiring fault that allowed the relay to back-feed it's coil circuit & latch. Occasionally it was a poor connection that didn't supply enough current to pull in but did supply enough to hold.

PC7060

capouch said:

“@PC7060 I had to do some flushing as part of the install. Lines are nice and clean, and again--things work perfectly 100% w/o the new radiator.”

Yes, but this is typical of highly restricted systems.  Provided the pump is adequately sized to operate with high head the restricted system will heat.  But if you add a bypass route similar to the new radiator, with very low head, the water will take the path of least resistance and starve the high head portions of the system. 

That’s why I mentioned the TRV, the modulating valve forces water back through the main lines when the heat has been satisfied in the single zone. In a stable heat situation, the TRV tend to operate in the closed / nearly closed position (high head) allowing just the minimum flow to maintain heat. 

Not a solution for all cases but helps when balancing parallel- series systems. 

mattmia2

You could measure the current to the circulator in both case but I suspect the difference it small. i would look in to what is feeding power to the RA832 and if the transformer and 120v contacts of the relay are jumpered to be supplied by the same source. Do the transformer primary terminals have 120v ac when the relay won't pull in?

Is the boiler gas or oil?

capouch

@mattmia2 I didn't have the presence of mind to check that when I was panicking in a home without heat in the middle of winter. Not sure when the next playing-around will be, but it will NOT be during this current sub-zero snap we're in atm. Thanks everyone for the comments and suggestions. Hope to get it figured out at some point.

neilc

how about a couple distant pictures at the boiler, and of the circ(s)
how many circulators?

capouch

@neilc I mention earlier in the thread that boiler pictures cloud the picture more than clarifying it: it's a utility room literally stuffed full of pipes--potable water, gas lines, current and some out-of-service boiler lines, and even a set of basement-vacuum lines. I took a picture; you just really can't see the forest there for the trees.

Two zones, two identical Grundfos circulators. One zone is first-floor radiators, other is upstairs radiators. I added a small radiator to the upstairs zone, but in the basement. Twice it has taken down the whole system.

neilc

maybe we can all stop over saturday morning, say 9am, you can buy the coffee,
#still smiling face