Poor Performing Zone

[mayhem]

I have a heating system in my house that we installed new when we built the house. System went live Summer of 2002, began regular use in winter 02/03. Basics that I know off the top of my head, its an oil fired Weil-Mclain boiler, 180k btu with a powervent. 5 zones total and the system is (I think this is the right terminology) a close loop system filled with Noburst glycol. Regular annual cleanings have been done to the system and regular testing by the cleaners have put it running about 86% IIRC.

Zone1 is hot water
Zone2 is living room
Zone 3 is Maser Bedroom
Zone 4 is back bedrooms (first floor) and first floor bath.
Zone 5 is basement heated floor.

I don't use it anywhere near as much these days as I used to because we havea woodstove in the living room that meets probably 80%+ of our heating needs. We use the boiler for hot water and occasional heat in the MBR and zone 4. Zone 4's performance is abysmal...the thing runs and runs and runs and the heat in the room with the thermostat ( a 12x14 bedroom) climbs very slowly. The glycol runs through the bathroom baseboard first, bedroom with the thermostat and then another bedroom (14x16) and then back to the boiler. For awhile the baseboards in the middle stage seemed poor performaing and the other 2 rooms would get warm considerably more quickly, now it seems like all 3 rooms but I'm having trouble gauging it.

I've cleaned the baseboards out, made sure to remove paper bits, crayons and kids toys, the bottom of the baseboards are al open to allow air in from the floor and largely unobstructed on top...some stretches are behind furniture for example, but nothing really spectacular. The other zones seem to operate properly and put out decent heat...MBR warms up alot more quickly than the little bedroom and it about triple the air volume.

Not really sure where to go from here. Is it possible the feed pipes to the zone are clogged and simply not passing as much warm glycol as they should be? Does the glycol need to be changed (I've heard it can turn mildly acidic over time...maybe this is the case and I've got some crap in there)? I have 15 gallons of it in jugs leftover from the install.


Thanks for your advice.

 

[ISeeDeadBTUs]

When one of my 6 radient zone stumbles, I drain water (I'm thin king I'm getting some air too) and turn the fill valve back on for the boiler, until pressure is restored. Seems to work. Prolly has nothing to do with your problem.

 

[mayhem]

Sadly no as I have no fill valve to add water. Its a sealed system and since it used to perform alot better I'm assuming its not air intrusion...of course I could be wrong too. Happened once before.

 

[ISeeDeadBTUs]

Um . . . there has to be a way to add water.

Doesn't there??

 

[Kawliga]

Um . . . there has to be a way to add water.

Doesn't there??

Since its a pressurized system there must be a domestic water makeup near the expansion tank? Maybe the valve is closed or not working correctly?

Just a thought...not an expert here

M

 

[bigburner]

Has to be an expansion tank. I would check the pressure,if there really isn't a fill valve it's probability low on pressure and/or there is a partial air lock in that zone. You can hook up a washer hose to a boiler drain and back feed it threw the valve. Just don't leave the hose on there because you don't have back flow prevention and could contaminate your water system.

 

[in hot water]

Usually those glycol systems are not connected to a fill system, to prevent dilution. So you will need to pump fluid in to purge any air out. you really don't want a fill valve on it. but a lWC low water cutoff switch is a good idea should you lose fluid.

Does it really need glycol, is it left un-attended or pipes in outside walls?

If you could use water you will get better performance, but it sounds like maybe a simple power purge might fix it, if it did indeed work at one point. Are you sure the circulator is running and on the correct speed?

With glycol you need more pump and the glycol does not transfer heat as well as water. Here is an example of what 50% glycol does in a system.

hr

 

[mayhem]

The system was installed with glycol in it, so there is no water fill valve. Only reason for the glycol (as I recall it) was becasue there was a concern about the pex in the basement slab possibly freezing and bursting, but I really don't know the risk of that. The system is rarely unattended...we don't take long vacations and never go away for more than maybe a night in the winter. Circulator is definitely running, but I don't know how to measure the volume being pumped through it.

So in order to add fluid, will I also need to open a pepcock or something to purge air out?

There is an expansion tank in the system. What sort of pressure should I be getting there, at what point in the cycle and how do I measure it? If I'm low on pressure does that indicate air in the system? Why would that not affect the other zones as well?