need help radiators not giving off enough heat

ed sarafian

I own an income property in toronto, it is a three story house with 5 units, the heating consists of a boiler and low slant-fin baseboards throughout the units. The boiler is a Teledyne Laars and the circulating pump is a Grundfos (43 - 75 F ). There is a thermostat on the main floor unit which controls the heating for the whole house. The plumbing for the heating system is copper throughout, with I believe 1 1/4" in the boiler room and in the risers and 3/4" slant-fins. The problem is that there is not enough heat being supplied to the units even though the boiler seems to be working all the time. The out-going and in-coming water heating lines from the boiler are practically at the same temperature, extemely hot, with barely a temp differential between the two. Tenants complain there is not enough heat, while they have the thermostat cranked right up but the unit (main floor apartment) just doesn't get warm enough especially on those very cold days.

Is it possible that the pump we have is too powerful, moving the water so quickly throughout the system that it doesn't get a chance to radiate the heat to the rooms and leave enough heat behind in the units?

Or is that we need to put more baseboards in the system?

I notice that when you put your hands around the in-coming and out-going lines by the boiler you can tell the water is moving very fast and you hear this sort of swishing noise in the pipes every so often.

I should also mention that according to the pressure gauge the psi is generally at 25 psi and it climbs to 30 psi when the system is really working hard, which seems very high considering the boiler units max psi is labeled at 30 psi.

Please help

Frank_17

base board

You have air in the system.
Purge out all zones

Earthfire

YUP

Sure does sound like AIR. purge it and then set your initial fill pressure at 12 to 15psi. that is plenty for the average 3 story building unless you have 20 ft. ceilings on each floor.

ed sarafian

baseboard rads

Please explain how to purge air out of the system?

What i have done is, go to each baseboard slant-fin starting from the basement, open the bleeder, and let some water out. oddly enough there was never air in any of the rads that i bled. Including the ones on the second and third floors. I also located a bleeder in the ceiling of the basement, bleed it but no air. On the third floor there are braukmann air bleeders, with a red plastic top with a pin hole on each of the slant fin rads. Some of them were leaking so I had to close them all the way, the other ones i left slightly open. I should also let you know that there is an expansion tank in the basement 6 feet from the boiler, I emptied it (very little water in it), could it be that there is too much air in the expansion tank?



The major underlying problem in this system is that the return line to the boiler seems to be the same temperature as the line leaving the boiler, in other words there in virtually no temperature differential between the incoming and outgoing lines. How can this be fixed? do you think the pump is to large I believe it's 1/4 hp grundfos pump, or do you think we don't have enough linear feet of baseboards through out the house?

Davel_3

No heat

You have air in the system, isolate each zone and purge one a a time, you may have to hire a contractor if you can not fix it your self. when you cannot hear the water moving in the pipes the air is gone,

John@Reliable

Tentants with no heat!, how to purge.

Ed, while purging a system is not hard to do, telling you how to do is? why you ask. There are so many whys your system could be piped that purgeing system the wrong way can and will cause your tenants to be even colder.I would find a good plumber or heating tech. to do and watch them.A building your size could take hours to do right but the pay-off is lower fuel bills and happy tenants. Also once system is purged make sure baseboard dampers are open and elements are clean for good heat transfer. Hope this helps.

jim bannister

poor heat

Ed,

Those black vents with the red caps are automatic air vents. The caps should be partially open to allow air to escape. If they leak, you can give them a half turn and remove the insides to clean. If your system is not airbound, check for a valve partially closed on either the supply or the return. Also, check to see if the circulator is actually working. The bseboards have adjustable louvers which should be fully open. If you only have a single thermostat for the whole house, you are never going to be able to balance out all of the floors. The thermostat will shut down when it senses heat in its' immediate area regardlesss of the other floors.

Online Sheriff \"Murph\"

simple question

are the base boards hot?? is the air convecting through them?? are they clean and unobstructed?? is the distance of the runs not over 70' long??


I think!!

ed sarafian

base board rad problem

I have this problem where the temperature differential between the in coming and out going water from the boiler is only about 5 - 7 degrees F. I have approximated that there is in total about 110 feet of 3/4" element in the 5 unit complex I own.

According to Dan Holohan's literature on loop hot water heating (found in Heating Q&A)the maximum amount of element you should have when using 3/4" element is 67 ft. in order to not have a geater differential of 20 degrees F. Well I have a 110 ft. of 3/4" element and only have a 5 degree F differential

I am confused!!

Please help, obviously something is wrong with the set up in my system.

Davel_3

Yo Ed

You need help on site, sounds like you don't beleve you have air in the system but if you can hear the water moving the pump IS working and you DO HAVE AIR IN THE SYSTEM, don't get wrapped up on the temp diff between supply and return, could be real simple fix or not, call a local contractor. It will be cheaper in the long run. Too many variables to trouble shoot by e-mail. And no I am not a contractor. GOOD LUCK