Indirect Fired Water Heater Troubleshooting Help

[beamd]

Hello all,

First post with a frustrating problem. For approx 2 months now, have noticed a lack of hot water. Less than 5 min in the shower (2.5gal/min) and it never really gets very hot like it used to.
I have a Weil Mclain Boiler (175000 btu) with an Amtrol 41 gal Boilermate indirect fired water heater. House heating is 7 zones of in-floor radiant Pex.
Here's what Ive done so far:
1) Initially thought it was just shower valve. Took moen shower valve out and purged the hot lines in case crud was in the line. Then replaced moen valve with new one...no workee
2) Drained and refilled boilermate. No sediment noted and have water softener as well.
3) Boiler temp seems appropriate as it cycles from 170-210F
4) Drained some water out of the boilermate and tested temp with kitchen thermometer. Withing 5 deg of demand temp on boilermate control.
4) Replaced the Taco 007 circulating pump on boiler supply line into the Boilermate (had hot temp on both sides of pump before replace but was told no way to tell if it was pumping enough water).
5) My amtrol troubleshooting guide has me cleaning the heat exchanger next. Problem is that I can't seem to find the commercial ice cleaner solution it calls for (phosphoric acid). Can I use vinegar or CLR? The other problem is that the hot water supply comes out of the top of the Boilermate on a tee with the T&P and line. No way to take the T&P off to put cleaner in unless I cut the hot water line (it's soldered).

Any thoughts or other things I should check for before calling pros in? I've been reluctant to call plumbers because I live fairly remotely and the travel charges are quite pricey.
Thanks for your thoughts,
Beamerflying

[jadnashua]

Often, a tank is plumbed with a tempering valve...the valve could have failed or someone turned it down. If so, it would be mixing in too much cold water.

[Redwood]

Probably looks like this...

[beamd]

I don't think I have a tempering valve. I think the hot water line out of the boilermate goes to a T&P valve and to my copper supply line into the home's domestic hot water supply.

[jadnashua]

I'm sure there are many installed without one, but where I live, a tempering valve is required, and is a reasonable safety feature. They do fail, though, so it is another maintenance item to worry about.

If the indirect is not getting hot, first I'd make sure the temperature sensor is fully seated in the well and that the connection to the boiler is intact. If you have the installation specs, and a multimeter, you should be able to check its operation.

When the storage temp is low, if the circulator doesn't turn on and fire the boiler, you'd have to check those controls. They could be relays, or solid state switches. You'd have to review the wiring diagrams and theory of operation in the installation manual.

[Karl White]

I had the same problem with my indirect heater. I drained the heater to move it and when I hooked it back up I filled the indirect (boiler water) first and then the direct side. After fighting it for a week I remembered that you have to fill the direct side and make sure all the air is out of the plumbing by opening upstairs faucets. Then I filled the indirect side and have had no problems since.