Balancing old gravity system

jbeck

Previous owner hacked an old gravity system (2 pipe direct return) into a 3 loop system. There is 1 B&G circulator pump on the return pipe.

Loop 1 - 5 radiators
Loop 2 - 11 radiators
Loop 3 - 4 radiators

In order to satisfy some rooms in the cold loop, other loops tend to get overheated. The thermostat is in the coldest room.

What would be some options to balance the system?

Ironman

Zoning it may be an option, but more info would be needed.

How about posting some pics that would show what the piping and boiler look like?

Paul Pollets

Install Thermostatic Radiator Valves (TRV's) on the supply to each radiator and you'll get the balance you want.

jbeck

@Ironman

Zoning may not be possible, as Loop 1 spans the 1st/2nd floor (back half) and loop 2 covers the front half.

Are there ways to balance the flow at the beginning of the 3 supply loops?

Globe valves, balancing valves, etc?

@Paul Pollets
TRVs sound good but 19 valves would be tedious...and pricy! In addition, some of the supply piping is very restricted and tricky to install (45 degree angles, etc)

Paul Pollets

It would be the last time you'd re-valved the radiators...and the system would balance.

jbeck

Are there any methods to balance the 3 loops using balancing valves / flow meters?

At the boiler, the supply forks into 3 pipes..then returns as 3 pipes into return.

EBEBRATT-Ed

You can install balancing valves on your supplies but if you have some hot radiators and some cooler radiators fed from the same supply pipe that won't work.

TRVs as @Paul Pollets mentioned would be the fix. You may not have to do all the radiators. Start with the rooms that overheat and do a few at a time. As you work with the valves and adjust them the system should start to balance

GBart

I had an old house once..........once.....the sheer volume of the water in the piping alone and the wasted energy it created really bothered me, so one spring I valved the boiler off for hot water only and cut all the black pipe out and repiped in copper (pex etc wasn't common then) 1/2-3/4 and zoned, I even made my bathrooms separate zones complete with digital t-stats for morning warm up , balanced beyond belief, ......I did it myself so the cost was low, still food for thought, the water in those black pipes is costly to heat, at the very least ensure they are insulated, you could be losing temperature on long runs and that can affect performance.

jbeck

How could I force more flow into the longest loop? And less flow into the shortest loop?


TRVs may not redirect enough flow into the longest loop, which is consistently colder than the other loops

SuperTech

Depending on the pipe size maybe you could install some Caleffi QuickSetter balancing valves and flowmeters, then you can easily and accurately balance the flow. My first thought was that TRVs would help a lot too. Is it possible to add zone valves or circulators and additional thermostats?

EBEBRATT-Ed

@jbeck
You can't put balancing valve on your three loops UNLESS one of those loops is cold. You need to tell us, do you have uneven heat between the loops? Or on each loop are some radiators hot and some cold

Different fixes for different problems