Hydro Hot Radiator Cap (getting it off)

[Stan Simpson]

I need to take my radiator cap off to check the fluid level. As you can see in the attached picture, to take it off requires downward pressure, and a twist. (Extremely difficult to exert downward pressure when your hands and body are below the plane of the cap). As soon as I do the twist, the edge of the cap that has to go down far enough to travel, catches on the screw that tightens the hose clamp. I would like to reconfigure the hose clamp, but I don't want to loosen it without knowing whether or not I'm going to get a bay full of boiler anti-freeze. Can someone tell me what will happen when I loosen that hose clamp?

[Steve Huber Co-Admin]

Stan,
If you follow the hose it should lead to the expansion tank. If so, that is the only fluid that you could lose. Suggest using a vise grip and clamping off the hose (needle nose vise grips work well for this). Then you can remove the clamp and cap. The only fluid loss then may be a bit from the main tank. Be sure to do this when the unit is cold.
Steve

[Stan Simpson]

Stan,
If you follow the hose it should lead to the expansion tank. If so, that is the only fluid that you could lose. Suggest using a vise grip and clamping off the hose (needle nose vise grips work well for this). Then you can remove the clamp and cap. The only fluid loss then may be a bit from the main tank. Be sure to do this when the unit is cold.
Steve

Excellent tip, Steve! Yes, the hose leads to the expansion tank, which is what I have always looked at to ascertain tank level. However, I have read here in other posts that I should actually be looking in the tank. I have a set of needle nose vice grips, so I'm good to go. I would love to meet the engineer who stuffed all of this stuff behind a 3 foot wide door, but that's another story! 

[Bill Sprague]

Stan,

Be happy you have a standard radiator cap.   Shortly before yours was built they used "boiler caps".  When the gasket ages out it costs up to $100 for the cap.   

[Stan Simpson]

Thanks for the help and suggestions.

Update:

I got the radiator cap off (the vice grips were invaluable) and was able to peer down in to the tank with the help of a strong light and a mirror. It was almost a pint low. Filled it to the brim, replaced the cap, fired 'er up and checked for leaks. So far, so good.

Hope everyone has a great weekend!

[Michael Rump]

All,

Just wanted to ask why it is necessary to look in the tank to determine the Aquahot fluid level???
I check the level in the plastic expansion tank when cold, then cycle the Aquahot until it shuts off.  I then check the hot expansion tank level and add as required to bring the level to the upper limit in expansion tank!
Of course you need to determine the fluid concentration and add either antifreeze or distilled water or a mixture of both.

Regards,

[Stan Simpson]

I believe I read on this forum (can't remember the author - perhaps the "Aqua Hot Guy" Orman Claxton, or the esteemed Ed Buker) that checking the expansion tank in the manner you describe is not sufficient.

[Gerald Farris]

If the expansion tank is level with or below the height of the top of the Aqua Hot unit, a defective upper seal on the cap will allow air to enter the coolant reservoir and it should be occasionally checked. But if the expansion tank is above the Aqua Hot unit, a defective upper seal will cause a coolant leak at the cap.

Gerald

[Michael Rump]

Gerald,

Thanks for the explanation. 

Regards,