Hi gang,

I have a problem. I bought my family house...the dreaded split level design with gas furnace and baseboard water heat. My father poorly wired and installed a dual zone heating system and wired in an electronic thermostat in the master bedroom, rather than use the old reliable mercury switch in the living room. I have an old Peerless MMW-115 gas boiler.

About 3 months ago I started to recognize that the system was constantly taking in air and causing the upper zone to remain cold. I was bleeding the system every other day unless I decided to leave the temp at 80 all day, at which point I would bleed it weekly or so. About 2 months ago I realized that the circulator pump no longer worked. The remote thermostat would only trigger the furnace to come on with several on/off switch flicks. Late week the valve for the upper zone started buzzing loudly. In my haste and frustration I disconnected it causing the boiler to no longer kick in.

Make a long story short, I removed all the wiring for the zone control valves and accidentally shorted out the Auquastat. I installed a new one in accordance to the manuals schematic.
Here is my problem:

1) I am attempting to convert the house back to a one zone system can the L8148J be used in that capacity?

2) I am not sure how to factor in the B2 terminal usage.

3) When I fuse the T an TV terminals the circulator pump will run, but the furnace will not fire up.

4) What should the water pressure in the furnace be set at? It always drops to about 10 when the heat is off.

5) Do I need to adjust the high limit dial stop?

Thanks in advance.

 

All is not lost. The L8148J should work ok regardless of how many zones you have. It doesn't know and doesn't care. If your circulator comes on, then the control is probably ok.
First off, your burner circuit is wired to B1 and B3. B2 is for millivolt applications only.
Make sure that terminals W & Z as well as Z & TP are jumpered with the brass jumpers or a piece of wire. (These are low voltage).
Your pressure should be at around 12 psi when cold. I don't think you could be pulling air into the system as you would have to get below 0 psi at the location air would be drawn in. What do you do to bleed the system?
Also leave your high limit adjustment at 180 degrees. This is the design temperature for the baseboards.

 

To bleed I let the pressure get up to about 30, anything higher and the release valve will open, close the valve for the lower level circulation, then open the upper level/zone faucet valve a little bit to push out the air until the pressure drops to about 20.

Now how do I get the furnace to kick in? Circulator works. pilot is on...furnace won't come on! *pulling hair out* Should it not come one when I jump the T and TZ?

 

Sorry, I couldn't refresh.

When T connects to TV, power goes from Z through a jumper to TP, through the relay contacts to B across to R and on to B1. When the circ is running, jump B to R, if it comes on, your high limit is the break.
If still no go jump TP to B.
Remember jumpers are for testing only, never leave them on, since they jump out safety controls & limits sometimes.

 

Let me just make sure we're on the same page with the basics.

I don't have to have B2 hooked up to anything.
L1-L2 are power. C1-C2 is Circulator. T and TV are open connecting wires that I am simply jumping for now rather than connecting to the thermostat. No other wires are put in/on.

I got the pilot lit and the knob to ON. When I jump T to TV, circulator comes on. After that I attempt to jump TP or B to R....and nothing happens.

Could my TR and TH be backwards? Do I need to adjust the High Limit?

 

The high limit should be at 180, but it should come on since the boiler is probably cold. Do you have a multimeter? If you do, test between B1 and B3, you should get 24 volts if it's working properly.
If not, test backwards to see where you lose it. Check R,B,TP and Finally Z.

There should be nothing hooked up to B2, unless it's a millivolt system.