I recently (in the spring) installed with a buddy a new Weil Mclean Oil fired boiler, everything was fine for awhile, but now (last 3-4weeks) I barely get any domestic hot weater and need to run the shower for over 5 minutes unitl it get's hot but then I only have a few minutes of hot water.. Any ideas? HELP

Did you install a tempering valve?

Did you install a storage tank?

Is your water hard water or have other debris in it?

Did this happen all of a sudden or did the hot water gradually go away over a few weeks period?

Yes there is a tempering valve, no storage tank it pulls hot water direclty from furnace (tankless heater) I don't think the water is very hard. I would say pretty much all of a sudden we cannot get good hotwater

I would suspect the tempering valve. It has the capacity to kill the hot water feed or open it to any position. Probably has dirt in the valve somewhere or it has gone bad.

One way to test is to remove the hot water line from the tempering valve and check the hot water flow. If plenty of hot water flows with in reason then the valve is bad. If it does not make a difference then it is the tankless coil in the boiler. Also check to be sure all valves are open in the lines.

You might also try to adjust the tempering valve to full hot and see if that makes a difference.

WARNING!!

Do not use the hot water without the tempering valve working properly. You can get scalded in the shower/tub or elsewhere.

Thanks!-I will give it a try and let you know.. Thanks for the advice. Hope it's just the valve.

Finally, found the Taco 5000 replacment tempering valve, installed it and it works great.. Thanks for the advice!