teledyne laars

Timco

Check along the supply side for a union. There is likely a thermostatic valve (thermostat) in the union that is stuck closed. I changed one recently and that baby fired long & steady again just fine. Sounds like the primary or bypass loop is heating and the boiler is cycling off on high limit. They heat the primary loop very quickly...

Tim

tom_49

teledyne laars problem?

Hi guys,

i got a no heat call today. So off I go to fix the problem.

I get to the house , HO says no heat on 1st floor. Problem ends up being a bad zone valve head, no big deal.

So I start to watch this thing, checking high limit etc. ( i dont have much experience with these boilers ).

1 zone is calling, around 70' of BB. Room is 63o. Boiler comes up to high limit ( 175o ) in about 30 seconds. Burner shuts down, pump stills runs. Temp on supply drops quickly ( 1 minute ) down to 135o, gas comes back on, same thing over and over.

Is this normal or what? doesnt seem to be a very efficient way to run a boiler.

Thanks, tom

tom_49

thanks Tim , I'll check that out.

There is no primary or bypass loop, its piped the old "standard way", pump on return, zone valves right above them, nothing on supply.

Timco

What type of Laars? If it is an EDP or similar, it has a pri pump / bypass inside the jacket and will run in bypass when the t-stat valve is closed.

Tim

Chas_2

past owner

i used to have a lars heater and i remenber that a full size by pass is require at a mimiun or p/s pipingf or what you will happen ,but being you may be the first to say some thing you'll get well it's always work and nobody ever said anything that's why if a couple of more years it will probalby start to leak .Personally my lars is gone it lasted about 16 or so years and she was piped to spec with by pass and still suffered ,but i am a realist and know nothing last for ever peace and good luck clammy

tom_49

Tim,

It is a mini-therm II ( jvt125 ).

I found the manual online and it calls for a bypass or p/s piping. I'll have to go back and install one. thanks for the help.

Timco

Use a thermic valve and it will be happier than just p/s. This one pictured runs very well. If your unit was reaching temp quickly, sounds like no flow through hx..

Tim

Bill Clinton_5

low flow

For some reason or other, there is low flow through that boiler. The load through that 70 feet of baseboard is probably 35 to 40 mbtu/hr, around 38% of the boiler's output
You should have 3.5 gpm or better through that loop and about twelve gpm through the boiler (which means primary/secondary is in order.

Bill