Tag Archives: district energy systems

Scale in Water to Water Heat Pump.

Water quality has come up as a major issue this year for the heating systems in Cheakamus Crossing.  High mineral content in the well water has created higher concentrations of minerals in the closed loop heating. The minerals of biggest concern, are calcium and iron.

The water supply is from the Whistler potable water supply, not, the District Energy System or Waste Water Treatment Plant, as some have asked.  It is certainly safe for consumption and people will even pay money to get the health benefits from mineral water, however, for a closed loop heating system, these minerals are a problem.

image of used copper piping
Calcium buildup on copper pipes

The copper pipes shown here, were recently cut out of a unit that had several leaking fittings. Water had been slowly seeping out through poorly connected pipe fittings.   As water leaks out, it is replaced by the boiler feed which adds fresh water and minerals to the system .   The pipe with the thick layer of calcium shown above, shows the bottom of the pipe, where heavier particles collect.  A  quick swipe along the inside, easily removes the layer of calcium, exposing the bare copper.  The calcium did not bond to the pipe, as  it would if on a  heated surface, however, it is still stuck.

The calcium can be removed or at least reduced from collecting in the piping with water treatment but not, by flushing.  It would take very high velocities to flush the calcium off the walls of this pipe.  Velocities, much higher than what can be achieved by draining the tank.

However, draining the buffer and adding fresh water,  will create more problems down the road.   For example,1-IMG_3098  the mineral scale shown here, is just some of  what was taken from one system that had a slow water leak that went unnoticed.   The build-up eventually caused the unit to shut down.  Now, a lengthy clean up process would have to be performed to remove all the scale.  Until then,  the scale will slowly build on to the heat exchanger plates, where it bakes onto the plates  and hardens,  like limestone.  Eventually, the unit shuts down on high pressure.

There have been contractors trying to sell flushing, as part of an annual preventive service which will actually have the opposite effect.  Flushing, is one thing that should be avoided except in extreme cases.

Fresh water contains oxygen, a key ingredient to rust.  Air bubbles trapped in the fresh water, can become trapped in various locations, adding minerals that  will build up over time.

For those that can actually access the drain at the bottom of the buffer tank, it may be possible, to bleed off some of the water with higher mineral  concentrations, from the bottom of the buffer tank but only after, it has settled over a long period.  Such as, September, after the water pump has been off all summer, there may be some sediment that can be removed.  Only drain off a few liters, at the most.   If the water has visible particles, then it may have helped.  If it is clear, then you may have done more harm than good.  If you break off that cheap little plastic valve, used as a drain fitting,  ( on some of the tanks) you will have definitely done more harm.

The piping practices are of concern on some units, which can affect the  life of the equipment, due to electrolysis.  This can shorten the life of the buffer tanks,  hot water tanks and other components.  I expect the  buffer tanks to last 20 years+ if properly maintained.   The larger hot water tanks, will be shorter due to the fresh water.

There are non-toxic ways to treat this water and to reduce the need for cleaning the heat exchangers.  However, you cannot flush your trouble away.

Water quality is key to the long term operation of these systems.   With proper treatment, the water can be improved at a reasonable cost and these heat pump systems, can run a very long time with very little or no maintenance.

 

 

Cheakamus DES Heat Pumps

There have been four compressor failures this year, that we are aware of, in the Cheakamus Development in Whistler, BC. At least two, and possibly the others as well, could have been prevented. If you have a Red Screen on your system, there is an issue with your heat pump that needs to be corrected. You can try to reset it once, but that’s it. Leave the Red Screen on and the system will use the electric back-up heat. Think of it as a car when the oil light comes on.

Scaling has become an issue, Well water is safe to drink, but it is full of minerals. These minerals result in scale inside the heat exchanger and will cause the unit to run hotter and over pressurize. If you continue to reset the unit, the compressor will burn out, then you will have to replace the compressor and clean the heat exchanger. This is a difficult process on these units, as they are hard to access. It also took sometime to find an effective chemical that did not damage the system, and still cleaned the heat exchanger. We do not know how often it will be required to be cleaned, however, I suspect once every few years. There are ways to improve the water quality, but it will always be an issue.

CC-heatpump

Gas boilers have the same problem in Whistler. Another issue is that the original capacitor, on the original Climate Master Heat Pumps, have been failing regularly. When the capacitor fails, it will cause the compressor to overheat and can result in compressor failure. The unit will not Red Screen (remember, like the oil light coming on in the car, to alert you for service) and will keep trying to run until the compressor gets smoking hot. If the original capacitor is still in place, it should be replaced ASAP. When you do call a service company, you need a Licensed Journeyman Refrigeration Technician to diagnosis the Heat Pump. If the company cannot send a Refrigeration Technician, call someone else. If you have a water leak, call the plumber, but an issue with the heat pump, requires specialized skills.

There have been a few issues with heat pumps, and several residents have spent thousands of dollars, only to have the systems misdiagnosed and still left with having to spend more money to have it fixed properly. I will not discuss the technical details of the issue, as this will result in unskilled people trying to resolve the problems. With heating systems this complicated, a little bit of knowledge is a dangerous thing. Here are a few simple things to look for:

-If the heat pump display is flashing “Heating” or “Hot Water” the compressor should be running within a few minutes. If you cannot hear the hum of the compressor, turn your heat pump off and use the back up heating.

-The two red water pumps, above the heat pump are used for circulating hot water for the potable hot water tank and the in-floor heating system. This pump should be warm when running but not hot. If you cannot comfortably hold your hand on the body of the pump, then it’s too hot. Turn the breaker off to the heating controls and call for service. The pumps are fairly tough and can handle a little over heating for a short while, but left unchecked it will burn up the bearing.
If you have items stored next to the heat pump, use precautions to prevent damage to wiring and piping. There have been a few cases, where a ski or boots have knocked a valve open or closed and shut down the system.

– Check the drain pans under the water storage tanks, these should be dry. Water in the pan indicates a leak that needs to be fixed. If the system leaks water, it will be continuously replenished from the feed regulator and operate normally. However, it will deteriorate the water quality of the heating loop and affect performance. This system was designed to have a low Green House Gas (GHG) foot print, and still have reasonable heating cost.

If you want cheap, use a High Efficiency Natural Gas. It is definitely the cheapest heating system available, but then there is that small issue of Climate Change and life on this planet, ending as we know it. The monthly operating costs on this system is low, however, you can expect to spend any savings on maintenance. Properly maintained, the maintenance cost will be reasonable, poorly maintained systems will not be. If you think the operating cost is high, just turn your heat pump to the off mode and let the electric heaters take over. You can check your daily consumption online at bchydro.ca, however, you do not want to wait the two month period for the bill to come in, unless you have money to burn.

For service on the system call Western Technical Systems at 604-849-0463