Problems after removing how water storage tank

[dyaco]

I recently had my hot water storage tank fail and removed it from the system completely. I replaced it with a passive mixing valve straight off the boiler. My boiler is oil fired and was installed in the late 90s. This unit also feels the baseboard heat in the 2 story 1800 sqft home.

things seems to be running fine for a couple of months. However is seems within the last few months my water temps have been fluctuating greatly.
temps at the showers and faucets seem to take forever to warm up, sometimes the shower only gets luke warm and sometimes scalding hot. It does seem like the water pressure drops slightly when the temp drops to luke warm to barley tolerable cold

I have tried adjusting the dial on the mixing valve and that outdoes seem to help much. There are only two people in the house, and I have the same problem with running nothing but the baseboard heat for hours and hours before. I am not sure if the cold New England weather would affect it at all.

I'm at a loss here guys. can anyone shed some light. any help is much appreciated

[jadnashua]

I'd need a bit more info to understand exactly what you've cobbled together there, but if I do understand what you've done, your boiler may not live long.

The tank acted like a buffer to help maintain a (small) supply of water and help heat the incoming cold water so you had a decent 'nominal' temperature output. Bypassing it means the outlet temp is entirely dependent on the volume used and the incoming water temp. Try to use more, it's in contact with the heat exchanger a shorter time, and it's cool. First draw after a long time, quite hot. Mixing valves don't react immediately. Your best bet would be to add an indirect WH tank as a priority zone on the boiler for your hot water supply.

Maybe with a little more understanding, something else would come up. What brand and model boiler do you have?

[dyaco]

I actually had the repair done by a licensed plumber. The storage take was just a storage tank, no heating element and it was not on a separate zone. 40 or 50 gal cap i believe. It did have a circulating pump on it.

My understanding is that he took a tap of the main line from the street as the cold in to the mixing valve and the "hot out" from the boiler that used to feed the tank into the hot side of the mixing valve. If I remember right the plumber explained to me that the storage tank is not common and most with my setup use the mixing valve is more commonly used.

I have a Weil-McLain P-WTGO-4

[Tom Sawyer]

Your plumber should have dropped the tempering valve below the coil. Hot water sits on the spring and weakens it. A replacement cartridge for the tempering valve will fix it for a while but the problem will return