Sizing Hot Water Return Pipe See also – Contact me
web site of appartementgipieres.nl, Solar Hot Water installers in NYC. Essentially a copper cap two pipe sizes than the solar pipe can be but can be dealt with by installing some flow restriction on the return piping. leisure pool, which is just meters away, via a district heating pipe. and hot water on top, for district heating return pipe (heating water) and cold water at [ ]. water and the (district) heating water flow pipe can be found [ ] installation in the low-pressure pipe, e.g. in the return flow pipe of a district heating substation. Cubeflow Hot Water Tanks Specifications & Sizing CUBE flow Electric with pressurized or gravity tanks; Hot Water – Return Pipe – Hot water can be circulated. proper design and sizing of the heating system and the heat source system. 1 K higher heating water temperature corresponds to an increase in power Connect the brine line to the flow and return pipe of the heat pump.
Roth heating circuit manifolds keep you cosy and comfortable. The flow and return pipes are staggered, which makes assembly easier. The heating circuits are connected It can be used for all Roth system pipes in sizes of 11 to 20 mm. current tab: Overview: Heat pump systems · Brine/water heat pumps · Overview. water and the (district) heating water flow pipe can be found [ ] installation in the low-pressure pipe, e.g. in the return flow pipe of a district heating substation. Cubeflow Hot Water Tanks Specifications & Sizing CUBE flow Electric with pressurized or gravity tanks; Hot Water – Return Pipe – Hot water can be circulated.
A return circulation pipe is sometimes provided in a hot-water system where it is desirable to have hot water available continuously at the fixtures.
Typically for systems where the distance from the hot water heater to the consumption fixtures exceeds 25 - 30 m. A smaller pipe with an inline pump is connected to a point close to the most distant fixture and to a point close to the hot water heater.
The pump can run continuously or intermittent circulating enough water to keep the temperature drop in the pipeline during low or no consumption within an acceptable limit.
Acceptable temperature drop can be 10 o C. The length of a pipeline inclusive the circulation line is m.
The total heat loss from the whole pipe line can be calculated as. Required water flow to limit the temperature drop to 10 o C can be calculated as.
Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.
We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.
Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server.
Long horizontal runs with minimal vertical rise had difficulty getting gravity circulation. The biggest problem to overcome was air trapped in the high point of the system.
They addressed this by connecting a regularly used fixture or an automatic air vent at the top of the gravity hot water circulation loop to allow any air to be vented.
If air was trapped, a large bubble would resist gravity circulation. A commonly used fixture to the top of the hot water riser vented air and allowed the gravity circulation to continue.
Gravity domestic hot water systems were commonly installed before the introduction of electricity and circulating pumps, and some have been installed in newer homes with moderate success.
Newer code requirements for water heaters require flappers or a device in the top of the water heater to prevent gravity circulation.
This makes the water heater more efficient during efficiency testing, but makes many older buildings that install new water heaters experience problems with respect to gravity circulation.
That is when it is time to install a circulating pump. Since the advent of the circulator pump, many improvements have been made. Early pumps were the same ones used on hydronic systems.
The pumps were made of ferrous metals with cast iron and steel parts, and most of them suffered corrosion problems or had rusty water shortly after being installed.
Hydronic systems were closed systems with air eliminators to keep air and oxygen out of the piping circuit. Some hydronic systems use corrosion inhibiting chemicals to help prevent corrosion of the ferrous metals.
Oxygen contributes to the corrosion process and domestic water systems are open systems with air and oxygen entrained in the water flow.
It is for this reason that hydronic pumps and piping can be black steel and cast iron ferrous metals, and domestic hot water systems should be non-ferrous bronze or stainless steel parts with copper piping.
Pump manufacturers have continually improved the materials, bearings, seals and efficiency of the circulator pumps. Recently, criteria for temperature maintenance for hot water systems in the models codes were changed from foot distance criteria to a foot criteria.
I wrote about this many years ago. I proposed code changes showing a maximum distance of about 25 feet from a circulated main or hot water source would be the ideal maximum distance to allow hot water within a reasonable time, but knowing that would have many industry groups upset with a requirement for recirculation systems in most residences and small buildings, I compromised and proposed a reduction to a maximum of 50 feet.
This would allow most residences and smaller buildings to not be required to have temperature maintenance systems. The code change did not pass the first time, but eventually it prevailed.
For other than Group R2, R3 and R4 occupancies that are three stories or less in height above grade plane, the installation of heated water circulation and heat trace systems shall be in accordance with Section C The controls on pumps that circulate water between a water heater and a storage tank for heated water shall limit operation of the pump from heating cycle start-up to no greater than five minutes after the end of the cycle.
A water distribution system having one or more recirculation pumps that pump water from a heated water supply pipe back to the heated water source through a cold water supply pipe shall be a demand recirculation water system.
Pumps shall have controls that comply with both of the following:. In the code change cycle, a change was presented to the model codes, and it was touted as saving water and energy along with reducing the time it takes to get hot water at a fixture.
The code change was the technology, demand recirculation. I testified against this technology because health and safety should trump water and energy conservation.
Many other in the backflow prevention industry have voiced concerns about this technology, but it fell on deaf ears at the code hearings.
The code committee voted on this change based on the thought of having instant hot water in their homes, and saving a little water was more important to them than cross-connection.
Many of the code committee members voted for this and commented that it would be nice to have for their own home. This code change will allow contaminated hot water to flow into the domestic cold water supply pipes.
I was all for allowing this technology in residential applications only, but the code allows it anywhere. So, there will be a condominium or apartment building where someone decides to install one of these demand circulator pumps under their lavatory to circulate hot water.
Now everyone in the building will be drinking water with high magnesium or aluminum content and possibly high bacteria content associated with new breeding grounds in the cold water pipes, which will be in the ideal temperature range for Legionella and other bacteria growth.
In addition, most of the people in the building will not get clean cold water to cook or brush their teeth with. I see this as a ticking time bomb and a lawsuit waiting to happen.
I prefer minimizing liability and designing hot water systems the correct way with a dedicated hot water return piping system in the original design.
The hot water return piping system should be properly sized and balanced. I will not design a building with a demand circulator connecting the domestic hot water to the cold water pipes.
Demand circulators are retrofit products for improperly designed systems, that should only be used in single-family homes where the homeowner will live with the consequences of using such a product.
Demand circulators should not be designed or installed in commercial or multi-family buildings because of the obvious crossconnection and water quality issues it brings with it.
Ideally, hot water should arrive at the fixture between zero and ten seconds from the time a faucet or fixture valve is opened.
There are a couple of manufacturers that offer fittings and designs to allow the hot water to circulate right up to the fixture, and some manufacturers allow circulation right up to the faucet spout, such as Kemper hygiene systems bit.
Surveys of how water users showed wait times between 10 and 30 seconds were marginally acceptable and wait times in excess of 30 seconds were considered unacceptable.
The following are a few considerations when piping the recirculated hot water return HWR piping:. The closer a circulated line is to a fixture, the less time it will require to get hot water from the fixture.
If the building has multiple hot water mains and branches, each branch should have a balancing valve and check valve before connecting to the hot water return main.
Simply installing the valves is not enough; after the system is started up, it must be balanced to assure each branch has the calculated flow rate to maintain the desired temperature in that branch.
This prevents short-cycling of the hot water through the path of least resistance closest branch circuit. I have investigated numerous systems with problems and the problems began because the system was never balanced when it was installed.
Untrained maintenance personnel find that there is no flow in the farthest portion of the piping system, so they install a bigger pump.
This typically does not solve the problem, but soon after the larger pump is installed, the piping system starts to spring leaks near elbows and valves.
Balancing the hot water system is a relatively simple process, but calculations must be performed and flows in gallons per minute must be determined for each balancing valve prior to setting.
Water flow velocity is very important in domestic hot water pipes with copper piping and brass or copper alloy valves. High water velocities, combined with hot water, can cause velocity erosion issues for the pipe and valve walls.
I often see half-inch pipe installed. Smaller diameter pipes create a condition where the velocity increases at the same flow rate, and it also causes system temperature differentials from the supply to the return temperature that exceed the design criteria of 5 F, 10 F or 20 F.
The Copper Development Association recommends a maximum flow velocity of eight feet per second for cold water flowing in copper pipes and five feet per second for hot water.
It also recommends a maximum velocity of two to three feet per second for hot water over F. These recommendations are sufficiently vague enough to lead you in the right direction, however, I have come up with a more accurate table for pipe sizing and a chart you should refer to in order to assure the flow velocities do not erode the pipe walls.
This table has worked well for me and should provide a system that will work without velocity erosion issues. Domestic hot water above F is not recommended because of the potential for scalding, and as temperatures get higher, the corrosion accelerates.
In some unique cases, domestic hot water temperatures can go higher than F booster heaters and steam heat exchangers, or with some types of heat recovery systems or other industrial or institutional piping systems.
In these cases, consider sizing the piping to keep velocities lower than two feet per second. When there is a mixing valve in the system, the tempered water return TWR must split and be routed to the cold-water side of the mixing valve and to the cold-water inlet of the water heater.
A balancing valve should be placed in the line going to the water heater and the mixing valve for flow adjustments if needed.
Please read AddThis Privacy for more information. If you want to promote your products or services in the Engineering ToolBox - please use Google Adwords.
Make Shortcut to Home Screen? Tag Search en: water pipes tubes sizes dimensions. Search the Engineering ToolBox. Privacy We don't collect information from our users.
Citation This page can be cited as Engineering ToolBox, With the very recent update of BS , these two standards have now fully replaced the long-standing — and now withdrawn — BS The control of legionella bacteria in water systems.
The technical requirements for DHWS are explicitly covered by the five parts of BS EN Specification for installations inside buildings conveying water for human consumption — general; design; pipe sizing; installation; and operation and maintenance.
Legionella is not transmitted from person to person, but is acquired by the inhalation of the bacteria, typically in a contaminated aerosol.
At low temperatures, legionella becomes dormant, but it is ready to multiply when the opportunity presents itself.
Biofilms are created through a combination of nutrients, scale and corrosion at appropriate temperatures, and provide an ideal breeding ground for legionella.
However, as is reiterated in BS , there are several statutory instruments in the UK that, although generally consistent with the standards, may alter some of the detailed requirements.
The Water Regulations Advisory Scheme WRAS website provides a useful summary of, and links to, the principal regulations and byelaws that control this area.
However, if undertaking design, it is important to refer to the primary source. Perfectly hygienic potable water contains bacteria and the nutrients that fuel legionella and other microorganism growth, and biofilms develop in all systems irrespective of the material used.
In order to reduce risks, there are several factors that should be avoided:. Trace heating could also be seen as a solution if there was likely to be an unreasonable length of time to draw off water before it became useably hot.
Chlorine dioxide Chlorine dioxide ClO2 is an oxidising biocide capable of reacting with a wide range of organic substances, including many of the constituents of bacterial cells.
Chlorine dioxide does not hydrolyse when it enters water; it remains a dissolved gas in solution. Chlorine dioxide is approximately 10 times more soluble in water than chlorine.
DHWS deadlegs should not exceed a volume of 0. This requirement is driven by the need to reduce legionella bacteria, but also reduces the risk of stagnation, ensuring better water quality.
This will reduce the risk of relatively stagnant water contributing to biofilm colonisation of the other outlets. When equipment or outlets are permanently removed, the branch pipework should preferably be removed rather than simply being capped off, so leaving an unwanted deadleg.
Circulating pump design, the correct commissioning of balancing valves, and positioning of non-return valves are key issues to ensure flow throughout all parts of the hot water system — particularly the hot water return legs — to avoid long lengths of stagnant pipework.
BS EN recommends that standby pumps should not be used, as non-operating pumps create stagnant pockets of water that pose a legionella risk.
Another oft-used pipework system component — the automatic air vent — should not be used, as it creates a stagnant store of water.
Good pipework design, and properly installed and supported pipes, can be used to ensure that any air is rejected as the water flows from the outlets and does not obstruct the return flow.