Q Hot Water Heating
You need to understand how everything works together in order to try and get to the bottom of it.
Beware of battling controls Continued from page 29
can about controls, because not only can they cause insufficient heat, they can seriously damage system components through their misapplication or improper settings. Boilers can short-cycle themselves to death for instance, just from an incorrect differential setting. It can be such a simple mistake. I moved into a brand-new condo years ago and heard the zone valve in the wall zipping open-closed, open-closed, every six seconds. The heat anticipator in the thermostat was just set wrong. I doubt if that valve would have lasted a month. Most homeowners would never have noticed it.
Heat transfer woes Air flow and heat transfer issues can cause all kinds of pain that may not be noticed until it gets really cold. Hydronic terminal units transfer heat to the space – mostly to the air. Look for plugged air filters, dirty radiator fins, curtains / furniture blocking or insulating
www.plumbingandhvac.ca
radiators. Radiant floor systems can have too much insulation on top (carpet or thick staple-up construction) or not enough insulation below. Lengthy, un-insulated hydronic distribution piping runs can waste their heat to places that don’t need it. Most of the problems described in this article can trigger the wrong people to crank up the boiler water temperature to compensate. Yes, this can temporarily “solve” the insufficient heat problem, but it will eventually return as the system continues to deteriorate. This is a huge issue when owners are trying to save energy with outdoor reset controls. When the problem is only in part of the building, the rest of the spaces can get overheated. Unfortunately, residents can eventually get to like it. Then you have big trouble trying to dial things back when you actually find and fix the original problem.
Fluid flow and heat transfer Fluid flow and heat transfer issues – I’ve saved the best for last. For some reason this is the one that stymies many troubleshooting efforts. Problems in this category are generally flow related, but occasionally one sees piping and terminal units insulated from the inside (gunk coating the wet side of heat transfer surfaces – be aware of the possibility). Boilers may also not reach their rated output, so learn how to clock a gas meter and confirm boiler input/output. Please see ‘Fluid’ on page 33
July/August 2018 – Plumbing & HVAC
31