L7224 settings after removing DHW from system

Catanz22

Hello, looking for help on new electronic aquastat settings after the DHW coil in my boiler was removed and replaced with a heat pump for DHW purposes.

I have a 20 year old burnham oil boiler and the aqua stat is currently set up as a warm start. HL 180 with 10degree diff and LL of 160. 

Can these settings now be changed to burn less oil? 

Also do any settings in the aquastat neeed to be changed now that it no longer needs to control the coil for DHW?

SuperTech

Change the low limit setting to off. 

Catanz22

I thought this creates a cold start boiler which causes condensing and would ruin the boiler, especially an older one

HVACNUT

Catanz22 said:

I thought this creates a cold start boiler which causes condensing and would ruin the boiler, especially an older one

During the winter, the boiler will never go cold, and any flue gas temperature below the Dew point won't be low long enough to cause damage unless the system has a really high water volume. 
If you feel you need to keep temperature on the boiler I would start with;
Hi- 160°
Hi diff- 15°
Lo- 140°
Lo diff- 10°

You can always raise the High later if needed. 

How many zones? If more than 1 and using a zone panel, then it should already be wired with ZR,ZC because the tankless was being used. That would keep the circulators off until boiler temperature reaches 140°.

Catanz22

HVACNUT said:

Catanz22 said:

I thought this creates a cold start boiler which causes condensing and would ruin the boiler, especially an older one

During the winter, the boiler will never go cold, and any flue gas temperature below the Dew point won't be low long enough to cause damage unless the system has a really high water volume. 
If you feel you need to keep temperature on the boiler I would start with;
Hi- 160°
Hi diff- 15°
Lo- 140°
Lo diff- 10°

You can always raise the High later if needed. 

How many zones? If more than 1 and using a zone panel, then it should already be wired with ZR,ZC because the tankless was being used. That would keep the circulators off until boiler temperature reaches 140°.

Boiler has 3 zones, all baseboards and only 1 is ever used. Each zone uses its own older style relays, not the new single board.

Im indifferent about keeping the low setting. I have no problem referring to an expert like yourself if you say to
then the limit off

bburd

If it's baseboard which is low mass, you should be safe from condensation running the boiler in cold start mode with the low limit off. Those systems reach high water temperatures fairly quickly.

If you had cast-iron radiators and old, large volume piping that would be a very different story.

HVACNUT

Catanz22 said:

Im indifferent about keeping the low setting. I have no problem referring to an expert like yourself if you say to
then the limit off

Whoever told you I was an expert fed you really bad info.

If it was my boiler, I'd turn the Low off, making it cold start. 

When the boiler is off for the season, maybe there will be some water weeping from the relief valve, or circulator gaskets, or boiler drain, or more common, the coil gasket. But those issues are easily remedied. If for some reason it starts leaking between the CI sections, then I would set a minimum Low setting of 135°

BTW, we don't know if the Burnhan is CI or a steel dry base. If steel, cold start all the way.

Catanz22

HVACNUT said:

Catanz22 said:

Im indifferent about keeping the low setting. I have no problem referring to an expert like yourself if you say to
then the limit off

Whoever told you I was an expert fed you really bad info.

If it was my boiler, I'd turn the Low off, making it cold start. 

When the boiler is off for the season, maybe there will be some water weeping from the relief valve, or circulator gaskets, or boiler drain, or more common, the coil gasket. But those issues are easily remedied. If for some reason it starts leaking between the CI sections, then I would set a minimum Low setting of 135°

BTW, we don't know if the Burnhan is CI or a steel dry base. If steel, cold start all the way.

Do I need to remove one any of these wires after removing the DHW coil from boiler 

SuperTech

No. Switch the low limit to off and you should be good to go