Coffee Break with Monte Karchner from Williams Comfort Products
What is an Integrated Piping System and how can it make a building more energy efficient?
We had the pleasure of hearing from Monte Karchner from Williams Comfort Products during our most recent Coffee Break webinar. In all our Coffee Breaks, we hear straight from the experts about the most relevant topics in HVAC (ask our sales engineers for an invite).
Most residential-type buildings, like hotels, assisted living facilities, dormitories and apartments, have three pipes for domestic water running everywhere in the building.
Karchner asks: What if you could use those pipes to also satisfy space heating and cooling requirements? Integrated Piping Systems (IPS) have been doing so effectively and safely, for the last 25 years.
The Tradeoffs in Heating and Cooling Systems
Let’s consider a standard four-pipe fan coil hydronic system. It’s an elegant, sought-after system, great for comfort control and efficiency. But the installation costs are considerable. It’s actually seven pipes in total: four for the heating and cooling and three for domestic water.
Other heating and cooling systems can be less expensive to install, but there are tradeoffs. Two-pipe fan coil systems require supplementary electric heat for managing the seasonal changeover. Water-source heat pumps require a compressor in every space and extra boilers in case there’s no heat to transfer. PTACs have huge operating costs and are the least comfortable.
A developer may not keep in mind the comfort of the occupants or the efficiency of the system¾they’re more concerned with keeping installation costs low. That’s why Williams developed IPS; to meet these low install costs, but not sacrifice energy efficiency and occupant comfort.
How Does IPS Work?
IPS utilizes domestic water piping for dual functions. The same system that feeds your shower or sink feeds into a terminal fan coil unit in each living space.
When the thermostat calls for heat, a two-way valve opens allowing 140°F HW to flow to a specific coil and heat the space. This setup eliminates the need for HVAC heat-specific equipment like boilers, storage tanks, supply and return pipes and pumps.
The domestic cold water system requires a small modification so it can supply both the water and the space cooling. A fourth line is added¾a domestic cold return¾to make it a continuous, circulating loop just like the domestic hot water loop. Then a chiller, isolated by a double-wall plate heat exchanger, is added for comfort conditioning requirements.
When thermostat calls for cooling, a two-way valve opens on a designated cooling coil, and 50°F CW provides the cooling. IPS delivers all your water, heating and cooling needs in four total pipes.
If you eliminate your heating boiler, what does that mean for the size of the domestic boiler?
Industry standards for sizing boilers ensure there’s usually significant redundancy, or more capacity that the peak load requires. With IPS you typically don’t need to upsize domestic water boilers. The storage tanks in domestic water systems also help deliver on extra HW demand.
What about the pipe sizing? If we’re increasing the load, won’t those need to be larger?
On a typical system, supply pipes won’t have to be upsized. DHWS pipes are sized based on the Hunter curve, or fixture count in the space. The terminal is another fixture for each space, but it’s only used in times of heating demand, and it’s not consuming water, rather skimming off the BTUs. The HW return pipe does have to be larger, because it is now it’s an actual return line and not a recirculation line.
Domestic cold water piping also needs to be upsized because a fan coil will place a larger than usual demand than your other CW fixtures. These pipes need to be sized to the chilled water requirement of the fan coils. Domestic cold water becomes a byproduct of that pipe.