ᐅ Install a 100-liter hot water tank without an expansion vessel

Hello, I hope I’m in the right place here.

I got a 100L (26 gallon) WMB or WWS (hot water heater / hot water storage tank) from eBay Classifieds (not sure which term is more accurate). It is intended only for the bathroom with the bathtub, toilet, and sink. The bathroom with the shower has its own 80L (21 gallon) tank, which unfortunately is not enough for the bathtub. Only about a quarter of the water in the tub is warm. That tank seems to be slowly failing.

I installed a safety group on the 80L (21 gallon) WWS because the shower is pressure-resistant.

For the 100L (26 gallon) tank, I would like to install a low-pressure fitting so the expanding water can be released through this.

Unfortunately, to continue using the bathroom stove I would need to redo the roof and rebuild or install a new chimney. That is too expensive and too much work for me right now. My wife is pregnant, and I want her to be able to have a warm bath if she wants.

So, the bathroom stove has to go (for now). But now I have no space for an expansion vessel and would therefore like to install this hot water tank as minimally as possible. Would it be sufficient if I

• install a check valve from the controlled ventilation system to the hot water tank
• run from the check valve to the fitting
• then connect both the controlled ventilation system and the hot water line to the boiler from the fitting

in other words, perform a classic low-pressure installation?

Could you please confirm if this is acceptable?

Best regards

You are actually in the wrong forum for this...

I’m very sorry, where should it actually go? Should I create a new post?

Best regards

No, I mean the wrong forum overall... this one is about house construction and less about DIY plumbing.

Well, maybe Joedreck, he knows a lot about gas, water, and plumbing issues.

You can operate a pressure tank with a pressure-reducing valve.
For this, you do not need a safety group, an expansion vessel, or a non-return valve.
The tank must simply be installed higher than the outlet fitting.