View Full Version : Monoflow problem

01-31-2007, 08:57 AM
The furnace is on half the time but the house is heating up only slowly (1-2 degrees per hour) and when it is 10F outside, it never gets hot enough. In other words, the heat is on downstairs but it does not propagate upstairs well. Any suggestions?

01-31-2007, 01:43 PM
What type of heating is it?
Forced air?

Some more info is required

01-31-2007, 02:55 PM
Do all rads have screwdriver vents?

01-31-2007, 04:36 PM
Um, how much pressure on the boiler? How many stories is your home? Finding out the elevation between the boiler and the upper most radiators will tell us what pressure you should be running.

02-01-2007, 01:04 PM
My heating system is a monoflow water heat with radiators. There is a ring of hot water in the basement and tlines going up. Above the basement there is two floors. There are screwdriver vents. I don't think bleeding is the problem.

02-01-2007, 02:19 PM
What sort of metering/regulating valves do you have on the basement loop?

02-01-2007, 07:43 PM
Make sure there is enough water pressure on the system. Turn the pumps off and bleed the radiators and bleed them some more. Start with the first rad. from the boiler and then go to the next in progression.

Some one asked you to post the water pressure in the boiler. What is it...........

02-02-2007, 05:26 AM
The boiler pressure is 17.

02-05-2007, 06:05 AM
The water temperature in the basement loop is colder when it enters the boiler than when it leaves. This makes sense, of course, but just how much colder should it be? Should the pump make any audible noise (it does not)? Where is the temperature of the boiler water measured - before or after the water enters the boiler (the boiler is on if the thermostat tells it to and if the water temperature it measures is more than 160 F).

02-05-2007, 06:24 AM
I still think you still have a lot of air. Monoflows can be hard to vent because the pressure is on both ends of the rads. Do you have a by-pass on the feed water? If you do, have some one open the bypass and watch the pressure gauge so it doesn,t get over 25 lbs. pressure and bleed like crazy. Or if you can set the pressure up a little higher to get more water to flow into the system.

02-05-2007, 06:46 AM
The radiators are all warm (not hot!). Is bleeding necessary then?

02-05-2007, 12:54 PM
May be..........

02-05-2007, 02:35 PM
It is useful to know both the supply and return water temps. On my radiant floorloops, it is set up for 130-degrees on the supply side, and right now (about 18-degrees outside), it is about 60-degrees on the return (this varies depending on the heat load). Note, some boilers are not designed to allow return water this cold.

A good circulator pump is nearly inaudible in most situations, at least on the ones I've played with (limited). If it is very quiet, you can hear them, or feel them slightly. Vibrations or noises may indicate cavitation (not good!), air pockets (also not good), or a bearing starting to go. Note, these use a water cooled/lubricated bearing - running them dry will ruin them quickly. Many circulators don't have much head (the ability to pump against a load - normally figured as rise). A closed system (one full of water without any air pockets) is much easier to pump than one with air. ANy air pockets in the line can prevent the water from flowing.