Now I noticed that hot water pressure in the house is very low. Hopefully saving some energy costs. My problem was that the upstairs thermostat only started the circulating pump. No more heating up to 500 and then turning on the pump when all you need is to pull off a temperature of say 90 degrees. So if the LO is set to 120 and the DIFF is set to 10, when the boiler temperature rises to 120 the burner turns off and the circulator is allowed to run - that is to circulate water out of the boiler to the baseboards or radiators. any suggestions, at AQUASTAT TROUBLESHOOTING The boiler was just cleaned last Friday and on Monday there was not hot water. The thermostat calls for heat and provided that the boiler temperature is below the CUT IN setting on the boiler primaruy control or aquastat the boiler will cut-on, heating its water. setting minus the differential.

We explain the location and use of the heating boiler reset button found on aquastats. Thanks for the note, Ken; I'm of course surprised as the blue wire is normally used as we described - but then yours is not an R8184 it's an L8124 aquastat; With it disconnected the HI limit ought to run the boiler;What were your aquastat settings for HI LO DIFF?Did you check to assure your other wiring connections are as given in the installation guide for this control? Third, ditto my second point above if you actually saw water temperatures above 250F at times - how is this POSSIBLE unless the boiler was under pressure? I keep getting Err 5 on aquastat relay.

season. Sounds more like the water in the pipes are in a warm area then a cold area and then finally the hot water gets to your shower.... pipes carry a lot of water and if you have an efficient shower head (recommended always) then it can take some time to get to the hot water from the heater especially if they are the old pipes and your shower is a ways (by pipe not necessarily actual distance to furnace).. You may want to trace the pipes from the shower to the furnace and see where it goes.. through walls which are on the outside of house vs inside, higher lower, etc and even turn the shower on as you hold the pipe at various places to see if what I say is true. To shut the boiler down for 23 hours each day? I cant thank you enough for your help. It's very well done and informative. Rather than raising the HI LO to make the water hotter, I'd consider partly closing the valves on the radiators that are early in the loop to slow the flow rate into them and thus give more heat to the later units. I want to disable the boiler/coil via the Aquastat in order for the incoming water to run thru the coil but prevent the boiler from firing when the temperature of the domestic hot water falls from the boiler at which time the electric system will take over.

So that when the boiler is in use in the winter for heating the house, the idea now is to allow the pre-heated water from the coil to flow thru the electric hot water system thus the electric system will be functioning only when the water temp. I have a indirect hot water heater. If it's a modern, physically smaller steel boiler, your cost to heat it up from cold will be less - but then your tankless coil is going to suck that heat out quickly when you're running hot water through the tankless coil regardless.

Can I disable the aquastat and how do I do it on that specific model?I installed a shutoff valve on the cold water pipe going into the coil, so right now there's no water going to the coil. I removed only the blue wire that is closest to the diff adjustment.