Tag Archives: heating

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.

 

 

Commissioning Authority

I have been in the HVAC Industry for 30 years and the amount of nonsense that goes on in any given project, never ceases to amaze me. Projects that run ridiculously over budget, technical equipment not functioning as designed, engineers that lower the bar to account for mistakes, and numerous other deficiencies that are passed on to owners.
The Construction Industry has changed extensively over the past 10 years, building structures and its systems are more complex. Systems such as, Communication Networks, Computer Servers, Surveillance Equipment, Building Automation, Sprinklers, Fire Alarms, tighter building envelops and complicated HVAC to mention a few. Added to this mix, are many new building codes that demand higher efficiency and stricter safety requirements. All these changes necessitate a higher level of skill which is increasingly difficult to hire as the skilled labour pool continues to shrink.

During this same time period, I have seen millions spent poorly and millions, needlessly added in future operating cost. Many owners and tenants have been disappointed to put it mildly. Had there been better planning in the beginning, a little more watch over the work site, during construction and proper commissioning on completions, a large amount of this money, could have been saved or, at the very least, better invested. Many new tenants and owners, would be much happier if they got what they paid for, instead of being stuck unexpected additional costs.

dirty filter-3
Heating Loop side stream filters

For example, this image is a water filter from a hydronic system. The building was less than 3 years old and there are serious mechanical issues. The mechanical system likely cost a million+ and, a particular filter was specified but never installed. The filter housing is worth $100.00 and was installed on the heating loop, afterwards. It was in place for about 2 hours before being pried from the filter housing. The muck on the filter is mostly iron combined with other contaminates. Some of the muck has been caught in the filter, much more can be found in every bearing, pump, sensor, valve, boiler and heat exchanger in this building. It will be almost impossible, to completely remove the material, the best you can do is to reduce it. It will cause damage to this mechanical system, for years to come and should have never been allowed to occur in the first place. The missing filter was not the cause of these issues but would have reduced the damage. In this case, the developer had a reputable design team, an experienced general contractor, and basic commissioning at the end of the project. So why did this problem occur and how would you prevent it from occurring again?

Would you like to know more?