Large heat imbalance between 1st and 2nd floors (Monoflow)

bgohn

I have a 1955 Cape Cod style home with a single-loop monoflow hot water system, with a significant renovation completed last year. The full saga of adding 2 panel rads to the system is chronicled here. The issue now is I have a large temperature disparity between the first and second floors - typically 6-8 deg F, and with a very cold day today (10F, Boston area) I cannot get the upstairs above 64F even with the circulator running all day. System worked fine before the renos.

Part of my earlier saga was the plumber leaving the circulator on with the system drained, which I only realized hours later when the circ started screaming like a siren. It's been 'working' since, but I'm now wondering if it could be damaged in a way that dramatically reduces the flow while still remaining quiet.

I have a new circ on order anyway, but trying to set my expectations…..

TIA
Bob

neilc

what's the boiler pressure?

and a general picture or 2, the whole boiler, circ(s), zone valve(s), expansion tank, floor to ceiling, wide angle shot, or 2

Jamie Hall

Oh joy. It is, in my humble opinion, almost impossible to get a monoflow system to come even close to a balance with conventional radiation. You really need to split the monoflow system off, with its own circulator and thermostat, from the new radiation, which would have its own. Then you'll have a fighting chance.

Edit: I just discovered your other thread, with a bit more information — perhaps most important, that the new radiators are, or are trying to be, on the monoflow system, and in this thread it appears that the imbalance isn't so much related to that by itself.

In which case… it is still a flow balance problem, but you may need to fix it by splitting the system so the first and second floors have independent loops, rather than my earlier note of giving the panel radiators and the old monoflow system independent loops.

EdTheHeaterMan

To be clear, in the diagrams of your original post, you indicated that some of the radiators that are on the first floor did not work until you had the plumber do a redesign.   

• Are all the first floor radiators operating satisfactorily now? 
• Next, are all the second floor radiators having the same problem, even the ones that were fine in the original design before the renovation?
• Are any of the second floor radiators fed with 2 diverters, one or the supply and one on the return?

These answers may help in the solution of the problem.

EdTheHeaterMan

If you answered Yes question #1 above, and I was contracted to solve the second floor problem this is the way I would do it.

1. Disconnect all the second floor radiators
2. Bypass or remove all the diverter tees. Either fix is acceptable

3. Then make home runs to the boiler from the pipes to the second floor

That way I could guarantee the result.

bgohn

re: photo of boiler - here you go. Pretty simple.

IMG_2301.jpeg

re: is 1st floor working ok? Yes. Some small imbalance between Kitchen and LR but not surprising given new rads and new spray foam insulation in kitchen and mudroom vs maybe (?) old cellulose in rest of house.

Re: upstairs convectors - all having same problem. 2 bedrooms and bath, 5 convectors in all, on 2nd floor. All anecdotally feel cooler than same size / age convectors downstairs (but not measured). 1 upstairs bedroom at beginning of mono flow loop, other at the end. All just one diverter T but some staggered/stacked (see diagrams in other thread.

Again, could compromised circulator be the issue? It ran dry for hours, eventually smoking and screaming. But been “working” for the year since.

bgohn

and FWIW, nothing touched upstairs during the reno, which was gut reno of kitchen and 1st floor bath and conversion of breezeway into mudroom, laundry/bath.

neilc

So only the one circ,

is there air upstairs? can you hear the water running?

bgohn

@EdTheHeaterMan - Thank you for the thoughtful response (once again!). That is exactly what I am planning to do if replacing the circ has no effect (and I am not optimistic it will, but its relatively simple to do). In fact, I will likely break the two upstairs bedrooms into 2 individual zones as (a) my wife and I use each bedroom as home offices (kids are long gone….) and have different ideas about what the ideal temperature is, and (b) one bedroom gets lots of afternoon sun and naturally heats a bit more than the other. I would also reconfigure the piping to pump away while I'm at it. This just not something I want to do mid-winter. (There is family lore of me "simply adding a zone" to my boiler 25 years ago on New Years Eve when it was 15F outside. Do you know it's hard to find a 1x3/4x3/4 c tee at 11PM New Year's Eve?)

@Neilc - I believe I bled each convector quite well when I redid everything and the system is quiet - no gurgling whatsoever. One of the convectors has an auto vent, and there is a Spirovent at the boiler. FWIW, I have to say the system has been pretty easy to bleed - no typical monoflow bleeding nightmares. To be clear, the upstairs convectors DO heat up, just not as hot as the others.

EdTheHeaterMan

@bgohn Doing the home runs to the boiler room and using a PEX manifold makes it easy to make each upstairs room a separate zone. Try something like this and you can put a valve actuator on each loop/radiator.

https://www.supplyhouse.com/Uponor-Wirsbo-A2700502-5-Loop-1-Stainless-Steel-Radiant-Heat-Manifold-Assembly-w-Flow-Meter

And 5 of these actuator motors https://www.supplyhouse.com/Uponor-Wirsbo-A3023522-Thermal-Actuator-Four-Wire with 2 thermostats will control each bedroom separately. Just connect the bathroom loop to one of the bedroom thermostats.

hot_rod

another option

IMG_9269.jpeg

EdTheHeaterMan

another idea is 4 of these and 2 zone valves will also do the job. https://www.supplyhouse.com/Bluefin-CM3-75PXZ-PXO-3-4-PEX-Crimp-x-Spin-Closed-Manifold-1-2-PEX-Outlets-3-Outlets. But you will need to add all the valves and purge stations separately. and it takes more time to build them.

Time is money in business so the premade manifolds are lower cost to the customer when My labor was involved. When it is your labor that's another story.  Save on material and put in sweat equity and your out of pocket will be less.   

By the way, if the new circulator does not work, that’s ok. You will need it for the second floor zone.  Don't use the same  circulator for both zones.  Let the monoflo zone have the new circulator.  Save the old circ for the new second floor zone.

Also read this book  Zoning Made Easy to help you design the new zone and understand the old zone.