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140 58 Street, Building B Suit 5H-5
Brooklyn NY 11220
Office 718 492-3057
Fax 718 492-3555

Tuesday, June 10, 2014

Why outdoor reset systems do not need thermostat.

Outdoor reset is a way of matching boiler output with heat losses of the house. It is based on the idea that heat losses of the house depend on outdoor temperature with all other parameters unchanged. The colder outside air, the more heat is lost trough the house walls, windows and roof, and more heat required from radiators to replenish this loss.  
And warmer outdoor weather requires less heating output from radiators. 
Now we ask ourselwes, how can we alter output of the radiator to match heat lost by the house? 
The answer lays in relationship between radiator output and average water temperature in the radiator. The cooler the water temperature in the radiator the less heat this radiator emits. 
So, controlling average water temperature in the radiator we controlling amount of heat this radiator sends to the house. And this is a principle of outdoor reset. We change  the temperature of the water circulating trough heating system in accordance with changes of temperature of outside air. This is simplified explanation but it is a valid explanation. What we need for implementation of this type of heating control is:
  1. Outdoor sensor to measure outdoor air temperature. 
  2. Sensor to measure water temperature going to radiators. 
  3. Control device reading information from these 2 sensors and changing water temperature according program. 
  4. Constant flow of the water trough the system. 


Where do we see thermostat in this picture? Nowhere. Because heating pump never stops pumping water trough radiators when temperature of outside air is below warm weather shutdown temperature. 
Even more. All contemporary modulating boiler are specifically designed to work on outdoor reset. 
90% of them even have outdoor reset build into boiler from the factory. Actually 100% of European made boilers have build in outdoor reset. 

And yet most of boilers installed in US do not have outdoor reset set up. 


Because traditionally in United States boilers are working at constant temperature and interrupteble flow.  Temperature of the water pumped to heating system is constant, usually 180F. But pump is turned on and off by thermostat according room temperature.  This type of control leads to swings of room temperature, and overshooting temperature setpoint resulting in poor comfort and high fuel bills. 

We can make an analogy with the car. Any car has 2  MPG numbers. One for city driving, another one for highway driving. Car is the same, gas is the same, driver is the same. But on highway car can drive twice s much miles per same gallon of gas. Why? Because the conditions of driving re different. 

Let's take our boilers off the street and put them on the highway. Get rid of this thermostat and get outdoor reset control. You will not regret. 

Monday, May 19, 2014

Sump or Drain Required for Oil to Gas Boiler Conversion?

Sump pump or floor drain is required near boiler. Pump must be high temperature type. Hard piped metal line (no rubber hose or PVC) connection to the sewer line with check valve installed.

1004.6 Boiler rooms and enclosures. Boiler rooms and enclosures and access thereto shall comply with the New York City Building Code and Chapter 3 of this code. Boiler rooms shall be equipped with a floor drain or other approved means for disposing of liquid waste.
1006.6 Safety and relief valve discharge. Safety and relief valve discharge pipes shall be of rigid pipe that is approved for the temperature of the system. The discharge pipe shall be the same diameter as the safety or relief valve outlet. Safety and relief valves shall not discharge so as to be a hazard, a potential cause of damage or otherwise a nuisance. High-pressure-steam safety valves shall be vented to the outside of the structure. Where a low-pressure safety valve or a relief valve discharges to the drainage system, the installation shall conform to the New York City Plumbing Code.
1008.1 General. Every boiler shall be equipped with blowoff/blowdown valve(s). The valve(s) shall be installed in the openings provided on the boiler. The minimum quantity and size of each valve shall be the quantity and size specified by the boiler manufacturer or the quantity and size of the boiler blowoff/blowdown valve opening.
1008.2 Discharge. Blowoff/blowdown valves shall discharge to a safe place of disposal. Where discharging to the drainage system, the installation shall conform to the New York City Plumbing Code.

Saturday, April 26, 2014

Boiler installation and boiler inspection requirements by DOB NYC

1. Boiler room doors must be fire rated and self closing. They must swing out from boiler- room. Not required for sealed combustion boilers.

2. A labeled emergency switch must be installed at each boiler room door. For open basements, switch at stairs is permitted.

3. Boiler room ceiling and walls must be enclosed. The inspector may approve a boiler replacement with small openings and write an ECB violation to the owner. Larger openings will result in first test failure.

4. Open basements must have fire rated material over boiler a minimum of 8' around.

5. Must have perforated DOB plans and boiler manuals on site at t time of inspection.

6. Plans must show boiler make, model & heat input; boiler room door swing & emergency switch; Fresh air location and size; chimney location material & size

7. Clean outs required at base of chimney.

8. Chimney or gas vent must terminate 2' above parapet wall and 10' away from higher walls.

9. Direct vent boilers may horizontally vent 7' above private sidewalks & driveways, 4' below operable windows, 4' to the side of operable windows, 3' above forced air intakes within 10', 3' above grade, 1' above doors, and 3' from inside corners of buildings. They may not horizontally vent over a public sidewalk (4' buffer required). Maximum of 350,000 btuh heat input for devices venting within a 10' radius. Venting into alleyways, small courts, under overhangs & terraces, or heat input over 350,000 btuh will be handled on a case by case basis. Any heat input is permitted at roof line or top of highest floor.

10. Fresh air intake must be directly from outdoors. Ducted combustion air supply must have a fire damper or have fire proof covering to outdoors. Direct vented devices are exempt.

11. Motorized fresh air dampers must have an external interlock switch with all boilers. 

12: Mechanical fresh air supply must have a flow switch and be interlocked with all combustion devices.

13. Gas only boilers with heat input under 2 million btuh must have a chimney cap.

14. Must insulate all new heating and domestic hot water piping in the boiler room.

15. Floor drain or indirect waste pipe required for relief valve discharge, boiler drains, backflow discharge, etc.

16. Boilers must rest on concrete base, filled concrete blocks or brick base.

17. Must have isolation valves on heating piping lines for all boilers.

18. Must have two low water cutoffs for every steam boiler. One must be a manual reset type. One must be a mechanical type.

19. Must have cleanout plugs on steam pressure control piping

20. No band iron for straps, must have hangers or rods for heating lines or flues.

21. Blow down piping on domestic water relief lines must be copper or brass.

22. Steam systems must have a Hartford loop.

23. Cold water feeds must be piped into the return piping minimum 2' from boiler..

24. All natural draft gas fired boilers with heat input over 350,000 btuh input going into a common chimney must have spill switches interlocked in series,

25. All gas fired boilers with barometric dampers must swing both ways and spill switched mounted on the bottom of the damper.

26. Dual fuel gas/oil fired devices must have the spill switch on top of the barometric damper.

27. All natural draft boilers in individual dwelling units must have CO/smoke detector wired in series to shut down boilers if activated.

28. All boilers with C.D.R. controls and low draft switches must be wired and working.

29. No chimney cap on oil fired devices.

30. Oil tanks must be removed or legally abandoned.

31. Oil fired flue must have cleanouts every 15'

32. Inside oil tanks 550 and above must have shut off valve at tank and anti-syphon valve after shut off valve.

33. Must have fire rated ceiling over inside oil tank a minimum of 3' over oil tank.

34. No compression fittings on oil piping

35. Oil pump sets for #2 & # 4 must be intermittent operation.

36. Oil fired burners firing 3 gph must have a DAR kit

Friday, April 11, 2014

Why co-generation is not an emergency generator?

  We are sometimes meeting with prospective clients  looking for emergency generators and stomping into cogeneration ideas. And common mistake is that people think that cogeneration systems can serve as emergency generators. In a sense some of them can, but their output is too small to support needs of the household during power failures.
  The purpose of these 2 systems is different. Emergency generators are designed to provide sufficient output in case of emergency.
   Co-generation  system is designed to keep electric meter as close to zero as possible. It is economically not justified to sell electricity back to grid, and it is expensive to buy electricity from grid, so why not keep it even?
  Sizing of cogeneration unit is matched to average electrical hourly consumption of the household, not minimum or maximum.

Tuesday, April 1, 2014

Long winter

We, here in NYC, had unusually cold and long winter, I had no time to update this blog,. meanwhile we found new product, YANMAR co-generation system, hope it will find its place on the market. It is cool packaged system, and what is remarkable it uses natural gas driven diesel  engine. I had always been diesel engines fan, having diesel driven vehicles  for me, my wife, and business.

Sunday, March 2, 2014

Flue gas losses

In the process of fuel combustion not all energy of combustion gets delivered to the radiators. Some  energy is lost in the process, particularly is vented trough the chimney. 

 Standard efficiency atmospheric boilers have continuous air flow trough the boiler hot surfaces  to the chimney and heat is lost outside. 

Heat losses in the atmospheric boiler amount to 12% of fuel costs and in condensing boilers are just a few percent. 
So, if he heating bill is around $5,000 a year , losses trough the chimney are about $500 per year alone comparing standard efficiency boilers to condensing boilers. 

Friday, January 24, 2014

Radiant heating?

This is first post since November. We were extremely busy this heating season.
 But I must blog some basics of radiant heating.
One of the simplified interpretations of the first law of thermodynamics is that 2 bodies in thermal contact will exchange heat until their temperatures will become the same. So, heat will be transferred from body with higher temperature to the body with lower temperature. This exchange can be done trough conductivity, convection and via heat waves.
Radiant heating is based on heating waves heat transfer, also known as infrared rays. This type of heat exchange is done directly from body to body. Because air is not a body , it is not getting heated. IT IS NOT GETTING HEATED. One more time. AIR IS NOT GETTING HEATED. And yet every single radiant heating system we are fixing is controlled by thermostat measuring air temperature.  
  Another thing common to all these installations is setbacks. Setbacks are periods of the day or night with lower room temperature settings.
 Now, radiant floors are made of concrete with embedded tubing. It takes about 10 hours to heat one up, and yet on every job I see thermostats with night and day setback settings, which stop water from heating the floor. This poor concrete slab has no time to even heat up!  This is just pathetic. Radiant floor must be heated up in beginning of heating system and cooled down at the end of heating season.
  Control of room comfort must be done trough slab sensors and/or outdoor reset of the water temperature flowing trough tubing. Water must flow trough the tubing constantly, non stop.