Preheating water with solar energy

 Solar energy is free and free is good.  I like the idea of preheating water with solar thermal panels and store the heated water in a tank. If the water in the solar water tank is not hot enough, a gas powered water heater can complete the job.

Does California discourage electric water heaters?

Does California discourage electric water heaters?

Contrary to popular belief, California does not discourage electric water heaters--use of electric water heaters, especially the heat pump water heaters, is encouraged.   Depending on where you are in California, you can use natural gas (or propane) or electricity to generate hot water.  California DOES want your water heater to be energy efficient so that our precious resources are not wasted. California Energy Code (Building Energy Efficiency Standards), Title 24, prescribes minimum energy efficiencies required for both gas and electric water heaters.

How would you know if you could use a gas water heater at a particular location in California?

Section 150.1(c)8 of the California Energy Standards (produced below) goes in detail about your choices.

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8. Domestic water-heating systems. Water-heating systems shall meet the requirements of A, B, C, or shall meet the performance compliance requirements of Section 150.1(b)1. For recirculation distribution systems, only demand recirculation systems with manual on/off control as specified in the Reference Appendix RA4.4.9 shall be used:

A. A single 240 volt heat pump water heater (HPWH). The storage tank shall be located in the garage or
conditioned space. In addition, meet the following:
i. A compact hot water distribution system as specified in the Reference Appendix RA4.4.6 in climate zone 1 and 16; and
ii. A drain water heat recovery system that is field verified as specified in the Reference Appendix RA3.6.9 in climate zone 16.

B. A single 240 volt HPWH that meets the requirements of NEEA Advanced Water Heater Specification Tier 3 or higher. In addition, for Climate Zone 16, a drain water heat recovery system that is field verified as specified in the Reference Appendix RA3.6.9 and the storage tank shall be located in the garage or conditioned space.

C. A solar water-heating system with electric backup meeting the installation criteria specified in Reference Residential Appendix RA4 and with a minimum annual solar savings fraction of 0.7.

Exception 1 to Section 150.1(c)8: For climate zones 3, 4, 13 and 14, a gas or propane instantaneous water heater with an input of 200,000 Btu per hour or less and no storage tank may be installed.

NOTE: The space conditioning system shall be a heat pump as specified in Section 150.1(c)6.

Exception 2 to Section 150.1(c)8: An instantaneous electric water heater with point of use distribution as specified in RA4.4.5 may be installed for new dwelling units with a conditioned floor area of 500 square feet or less.

Exception 3 to Section 150.1(c)8A and B: A 120V HPWH may be installed in place of a 240V HPWH for new dwelling unit with one bedroom or less.

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Consider the following examples not involving a re-circulation system or solar heating.

Example 1: You are building a new home of around 1200 sq. ft. in San Jose.  What type of water heaters are allowed?

San Jose is in Climate Zone 4.  You are allowed to use an instantaneous gas water heater (when using heat pump for space heating and cooling).  You are also allowed to use an electric water heater that is a heat pump water heater.  Because your floor area is over 500 sq. ft., you are not allowed to use an instantaneous electric water heater (electric resistance heating).  And you are not allowed to have a storage type gas water heater.

If first cost matters most, you will go with an  instantaneous gas water heater.

If operating cost is of concern, and you don't mind a slightly longer payback time, you will be better off installing a Heat Pump Water Heater.

 

 Example 2: You are building an ADU of around 400 sq. ft. in Los Banos.  What type of water heaters are allowed?

Los Banos is in Climate Zone 12.  You are NOT allowed to use an instantaneous gas water heater.  You are allowed to use an electric water heater that is a heat pump water heater.  Because your floor area is less than 500 sq. ft., you are allowed to use an instantaneous electric water heater (electric resistance heating).  And you are NOT allowed to have a storage type gas water heater.

If first cost matters most, you will go with an  instantaneous electric water heater.

If operating cost is of concern, and you don't mind a slightly longer payback period, you will opt for a Heat Pump Water Heater.

 

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Images, courtesy of California Energy Commission.

Tags: California allows electric water heaters

California discourages electric water heater

California does not allow electric water heating

Only gas water heaters are allowed in California

Are electric water heaters banned in California?

Are electric water heaters illegal in California?

 

Difference between Mold and Mildew

 

Difference between Mold and Mildew

 

Mildew is also mold but it has just arrived and it has not penetrated the surface.  When I find ‘mold’ on metal I call it mildew.  Mildew is what you will find on metal window frames.  Mold is what you will find on your bread.  On a drywall: if it is new and can be easily wiped off, it is mildew; if it is old and has penetrated the drywall, it is mold.

1365 Magnolia Avenue, Redding, CA 96001

A property condition assessment done in October 2018


1365 Magnolia Avenue, Redding, CA 96001
Multi-Family residence
Built in 1952
Total: 24,512 sq. ft. of habitable space

County: Shasta County

Site:
APN: 15310018
Acres: 0.96 acres [200 ft. X 210 ft.= 42000 sq. ft.]

Topography:
Relatively flat with slight slope towards creek to the south

Fencing around the property:
north: CMU retaining wall with wood fence on top
east: CMU retaining wall with chain link fence on top
south: CMU retaining wall along the creek

Parking:
Asphalt parking spaces in the rear (east) and side (south)
Total car port parking spaces: 41
Total uncovered parking spaces: 4
Total parking spaces: 45
ADA parking spaces: 0

Structure:
Two L-shaped two-story structures.
No basement
Concrete slab
Wood structure
Pitched Roof with composite shingles

Storm drainage:
Gutters with downspouts, courtyard side of the two buildings, take water to City storm drain.
In between the two structures and on north and south ends, pitched roof drops water to flatwork, sheetflow to drainage basins.

Facade:
Some wood siding
mostly stucco

Housing:
Total of 40 apartment units

Beds    Baths    # of Units    Average SF   
Studio    1 Bath    12    468 SF   
1 Bed    1 Bath    24    636 SF   
2 Beds    1 Bath    4    908 SF   

Amenities:
Office on second floor of north-side building
Laundromat on first floor (east end) of of north-side building
[2 washers, 2 dryers]
Laundromat on first floor (east end) of of south-side building
[2 washers, 2 dryers]
Elevated swimming pool (north-east corner of the property)--not heated; chain link fence around the pool;
BBQ area between the two structures
Designated smoking area in the rear parking space


HVAC:
electric heating
window air conditioners

Electricity: [City of Redding]
Each apartment individually metered.
240 V, 200 Amp to each apartment

Gas: [PG&E]
Each apartment individually metered.

Water: City of Redding

Sanitary Sewer: City of Redding

Storm drain: City of Redding

Trash: City of Redding

Seismic Zone: 3 (Peak Ground Acceleration:0.30g or less)

Flood Zone: Zone X Unshaded, defined as areas of minimal flood hazard.

Wind Zone:  I (130 mph)

Is an undersized gas line a safety concern?

 Is an undersized gas line a safety concern?

 

As a designer I often run into undersized gas lines.  This normally happens when more gas load is added to a correctly sized gas line.  For example, you have a 1” line serving a total load of 148 cubic feet per hour at a maximum length of 100 ft., but then you decided to add one more appliance that uses 50 cubic feet per hour of natural gas.  The existing one-inch gas line now becomes undersized. When all appliances are simultaneously working, the equipment that is farthest from the gas meter will hurt and you will not have the necessary gas flow to make the equipment run at its optimum condition.  

 

When does an undersized gas line become a safety issue?

In most cases an undersized gas line is not a safety concern.  If an appliance were going to use 100 Cubic feet per hour of gas, and now, because of the undersized gas line, it is getting only 50 cubic feet per hour then the appliance is only going to produce half the amount of heat it would have produced with the correctly sized gas line.  But under-performance of an appliance is not a direct safety concern.  It is just a myth that an undersized gas line helps build Carbon monoxide.  A combustion process using a hydrocarbon (such as the natural gas or Propane) produces Carbon dioxide and water (Carbon of the hydro-carbon fuel binding with Oxygen to produce CO2, and Hydrogen of the hydro-carbon fuel binding with Oxygen to produce water).  Carbon monoxide is produced when there is incomplete combustion i.e., there is a shortage of Oxygen (air).  An undersized gas line WILL NOT produce CO because you are not cutting down on air (Oxygen), you are reducing the amount of hydrocarbon to be burned.
An undersized gas line can be a safety concern in a quite different scenario.  Imagine a burner working with the optimum amount of fuel (gas) and air being delivered to it.  Now start reducing the amount of gas to the burner but keep the air coming in.  If the excess amount of air can put out the fire, then you have stopped the combustion process, but you still have the gas flowing to the burner.  In such a scenario the gas buildup can be a serious safety concern.

Tags: Low gas flow, health hazard, safety hazard, explosion, gas pipe sizing, gas line sizing, gas sizing, natural gas, Propane, Methane, Uniform Plumbing Code, Gas chart

Undersized gas line an explosion hazard?

Undersized gas line creating a health concern?

Elevator Control Room Air Conditioning

 Keep your elevator control room HVAC system simple.  If the elevator machine room is on the roof, and the room does not have fire-rated walls, you can use an exhaust fan to take the heat out of the room.  Bring make up air using a wall grille.  If the elevator machine room is surrounded by other spaces and the walls are rated, use a small split AC unit to cool down the room--the refrigerant pipes and the condensate drain penetration through the rated wall have to be protected.

 

 

 Tags

Elevator Control Room Air Conditioning

Elevator Machine Room Air Conditioning 

Elevator Room HVAC

Elevator Room Cooling in Northern California

Was Aluminum wiring ever used in California?

During the 1960s and 1970s, when Copper prices were high, Aluminum wiring as a replacement of Copper was used throughout North America.  And yes, many properties in California too were constructed with Aluminum wiring.  How do I know?  I assess properties.  A property I recently assessed in Northern California had Aluminum wiring that was replaced with Copper in 2018.   And before that, Aluminum wiring was reported by the owner of an apartment complex in Stockton--in August 2019.

 

Tags

Aluminum wiring hazards

Aluminum wiring fires

House burned down because of Aluminum wiring

Replacing Aluminum wiring with Copper

California Energy Commission Title 24--2019 Building Efficiency Standards for Residential and Non-residential buildings

 

 

 

I recently completed a job that is still in the design phase.  I had to show energy compliance of the building shell (envelope).  Any residential or non-residential building being constructed in California on or after January 1, 2020 has to comply with the latest 2019 Building Energy Efficiency Standards.  I was pleasantly surprised to find out that the California Energy Commission has done some hard work to consolidate many features from the Energy Standards and the Appendices in the Adobe documents (forms) that you need to fill out to show energy compliance--in my case the 2019-NRCC-ENV-E form.  For example, when you enter the zip code of the property you are showing compliance for, the form automatically populates the Climate Zone box for you.  Similarly, you don't have to look into the joint appendices to figure out the U-value of a certain type of construction e.g., 2X6 wood framing with R-19 cavity insulation; you select one of the options available through a drop down menu and on your selection of the option, the form automatically populates the box of the U-value for that particular option. [Note that in previous energy standards the tables for Prescriptive Compliance showed R-values that you had to comply with; in the 2019 Energy Standards it is the maximum U-value that is specified in the tables.] 

Overall, the California Energy Commission has done a decent job in creating the 'intelligent' PDF documents for energy consultants to work with.  Kudos to the CEC!