US20070205293A1

US20070205293A1 - Heated fluid distribution apparatus for combined domestic hot water supply and space heating system in closed loop

Info

Publication number: US20070205293A1
Application number: US11/366,317
Authority: US
Inventors: Tae Kwak
Original assignee: Kyung Dong Boiler Co Ltd
Current assignee: Kyung Dong Boiler Co Ltd
Priority date: 2006-03-01
Filing date: 2006-03-01
Publication date: 2007-09-06

Abstract

A combined domestic hot water supply and space heating system includes a single water heating system, one or more space heating systems and a heated fluid distribution apparatus. The apparatus has piping that provides communication between the apparatus, the water heating system, the space heating system, a fresh water source, and a house tap. The apparatus also includes a by-pass heat exchanger that has a heat source side that communicates with the water heating system, and a space heating system side that communicates with the space heating system.

Description

BACKGROUND OF THE INVENTION

The present invention is related to a system that provides both domestic hot water and space heating. More particularly, the invention is related to an apparatus that properly distributes heated water from a singe water heating system to domestic hot water and closed loop space heating applications.
Most building or houses that require a domestic hot water supply as well as space heating use separate appliances for each purpose. For example, a conventional tank type gas water heater or an electric water heater has been used for domestic hot water supply. Conventional tank type gas heater or electric heater has disadvantage that it takes significant amount of space and it continuously lose heat energy due to its stand.
Conventionally, when space heating is required, a separate furnace or any hydronic space heater has been used. The furnace or heater has its own gas burner or electric heating element. This scheme is inefficient and waste space and energy.
A more compact and efficient hot water and space heating system has long been in need.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a compact and efficient combined domestic hot water supply and space heating system.
Another objective of the invention is to provide a fast, safe and reliable combined domestic hot water supply and space heating system.
In order to achieve the above objectives, the present invention provides a heated fluid distribution apparatus for a combined domestic hot water supply and space heating system. The combined domestic hot water supply and space heating system includes a water heating system and a space heating system.
The heated fluid distribution apparatus includes a cold water inlet fitting that is adapted to be connected to a fresh water source, a hot water outlet fitting that is adapted to be connected to a house plumbing fixture, a water outlet fitting that communicates with an inlet of the water heating system, a water inlet fitting that communicates with an outlet of the water heating system, a space inlet fitting that communicates with a space heating system return fitting of the space heating system, a space outlet fitting that communicates with a space heating system inlet fitting of the space heating system, and a by-pass heat exchanger that comprises a heat source side that communicates with the water heating system, and a space heating system side that communicates with the space heating system.
The apparatus further includes a primary circulation pump and a secondary circulation pump. The heat source side of the by-pass heat exchanger includes a source inlet that is adapted to communicate the water heating system, and a source outlet that is connected to the primary loop pump, wherein the space heating system side of the by-pass heat exchanger includes a space inlet that is connected to the secondary loop pump for reheating water from the space heating system and a space outlet for returning heated water to the space heating system. The working fluid directions are opposite with each other between the heat source side and the space heating system side in the by-pass heat exchanger.
The apparatus further includes a priority device, a three way valve and a control board for prioritizing domestic hot water. The priority device is connected to the control board. The control board controls activation and deactivation of the three way valve, the primary circulation pump, and the secondary circulation pump. The control board is adapted to communicate with a house room thermostat for turning on/off of the space heating system.
The three way valve communicates with the water inlet fitting, the source inlet of the by-pass heat exchanger, and the hot water outlet fitting.
The apparatus further includes an expansion tank and an air separator between the space outlet of the by-pass heat exchanger and the space outlet fitting. The expansion tank and the air separator balance pressure and automatically eliminate air in water flows.
The apparatus further includes a thermostatic mixing valve, which communicates with the space outlet of the by-pass heat exchanger and the space inlet fitting, and includes an outlet that is connected to the space outlet fitting.
The primary circulation pump communicates with the source outlet of the by-pass heat exchanger and the water outlet fitting. The primary circulation pump provides water head that is high enough to activate a flow sensor for the water heating system.
The secondary circulation pump communicates with the space inlet fitting and the space inlet of the by-pass heat exchanger. The secondary circulation pump has a predetermined flow rate, which is determined depending on the space heating system.
The apparatus further includes an anti-scalding valve, wherein the anti-scalding valve communicates with the cold water inlet fitting and the water inlet fitting and has an outlet that is connected to the hot water outlet fitting. The temperature of water from the anti-scalding valve is set to about 120° F.
The apparatus further includes a temperature and pressure gauge that indicates incoming hot water temperature from the outlet of the water heating system.
The apparatus further includes a water check valve that prevents return water backflow to the cold water inlet fitting.
The water heating system is an on demand flow through tankless water heater. Alternatively, the water heating system is a fully modulating device, which can supply hot water at a predetermined temperature ranging from about 100° F. to about 180° F.
The present invention utilizes an on-demand water heater, which is small enough to hang on a wall, as a water heating system. Sine the water heater has no reservoir tank, the water heater takes significantly less space compared to conventional water heater. Fully modulating computer controlled gas valve brings out significant energy saving. Automatic flow adjustment valve supplies hot water at desired temperature without temperature fluctuations. Various sizes of input water heating system can be used anywhere.
The present invention wisely controls conjunction of hot water supply and space heating with flow through type water heating system and space heating. Combining domestic hot water and space heating system involves a lot of confusion and difficulties in practice especially in controlling heat generation system, heated water temperature and flow rate.
The present invention supplies and maintains potable domestic hot water at steady temperature, maximizes efficiency in output BTU in supplying hot water, and maximizes efficiency in space heating by optimized control for radiant floor heating system, snow melting system, base board heating system, or force air heating system with a single flow through water heating system. The single flow through water heating system adopts an on-demand tankless water heater or an instantaneous water heater.
The present invention utilizes an open loop system and a closed loop system simultaneously. The open loop system is used for domestic hot water supply, and the closed loop system is used for space heating.
The present invention may be applied for various space heating system and wide area applications. For flow through water heating system that offers between 110,000 BTU/hour to 350,000 BTU/hour, the present invention can continuously produce hot water from 2 GPM to 12 GPM with 77° F. rise from ground water temperature. The present invention uses this hot water effectively to the combination of domestic hot water supply and space heating.
The distribution apparatus is used for distributing heated water to potable domestic hot water supply and space heating with the single water heating system.
The apparatus includes the priority device for supplying domestic hot water, the anti-scalding device, the by-pass heat exchanger, the circulation pump for space heating, the circulation pump for the primary loop, and safety and performance devices.
The single water heating system is a flow through type, and has the inlet for replenishing the system with unheated water and the outlet for supplying heated water. The water heating system can be set to provide hot water at 100° F.˜180° F. depending on the space heating system.
The space heating system includes a radiant in floor space heating, base board space heating and forced fan assistant space heating system. The temperature drop through the space heating system is designed to 14° F.˜35° F. on average using predetermined water flow rate and hot water temperature.
The by-pass heat exchanger transfers heat in 200,000 BTU/hr from one liquid medium to another with no intermixing of the two mediums.
Although the present invention is briefly summarized, the fuller understanding of the invention can be obtained by the following drawings, detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will become better understood with reference to the accompanying drawings, wherein:
FIGS. 1 a and 1 b are perspective views of a heated fluid distribution apparatus for a combined hot water supply and space heating system according to the present invention;
FIG. 2 is a schematic diagram showing the heated fluid distribution apparatus;
FIG. 3 is a schematic diagram showing the combined hot water supply and space heating system;
FIG. 4 is a schematic diagram showing a water heating system; and
FIGS. 5 a and 5 b are schematic diagrams showing space heating devices.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 a and 1 b show a heated water distributing apparatus 32 according to the present invention. FIG. 2 shows that the apparatus 32 has a cold water inlet fitting 21 for connection to a filtered and treated water source (not shown) as a potable fresh water source. The apparatus 32 also has a hot water outlet fitting 23 that delivers domestic hot water at a predetermined temperature, which is set about 120° F. The domestic hot water outlet fitting 23 normally supplies the household potable hot water via potable hot water taps or any plumbing fixtures that use potable hot water.
FIG. 3 shows that the apparatus 32 has a water inlet fitting 24 that is connected to an outlet 2 of a water heating system 31. The apparatus 32 has a water outlet fitting 22 that is connected to an inlet 1 of the water heating system 31 for replenishing unheated water.
The water heating system 31 is an on demand flow through tankless water heater, and uses gas (Natural gas or Propane gas) or electricity. Alternatively, the water heating system 31 is a fully modulating device, which can supply hot water at a predetermined temperature ranging from about 100° F. to about 180° F.
The cold water inlet fitting 21, the water inlet fitting 24, the water outlet fitting 22, the hot water outlet fitting 23 of the apparatus 32, and the inlet 1 and the outlet 2 of the water heating system 31 are made of ¾″ copper pipe and fittings.
The apparatus 32 has a space outlet fitting 20 that is connected to a space heating system inlet fitting 27 or 29 as a heated water supply fitting, and a space inlet fitting 19 that is connected to a space heating return fitting 28 or 30 as a return conduit for reheating water. The space inlet fitting 19 and the space outlet fitting 20 of the apparatus are made of 1″ copper pipe.
Referring to FIG. 2, the apparatus 32 has an anti-scalding device 9 for setting domestic hot water supply at 120° F. The anti-scalding device 9 is connected to the inlet fitting 24 and the cold water inlet fitting 21, and it has an outlet that is connected to the hot water outlet fitting 23.
The apparatus 32 has a priority device 8 for prioritizing domestic hot water. The priority device 8 is connected to the control board 26. The control board 26 controls activation and deactivation of a three way valve 11, a primary circulation pump 15, and a secondary circulation pump 16.
The apparatus 32 has a temperature and pressure gauge 7 that indicates incoming hot water temperature from the outlet 2 of the water heating system 31. The temperature is between 100° F.˜180° F. depending on the temperature set in the water heating system 31. The temperature and pressure gauge 7 is used to prevent high temperature replenish water.
The apparatus 32 includes a water check valve 14 that prevents return water backflow to the cold water inlet fitting 21.
The apparatus 32 includes a by-pass heat exchanger 25. The by-pass heat exchanger 25 transfers heat from the water heating system 31 to the space heating system 33, 34. The by-pass heat exchanger 25 includes a source inlet 46 communicating with the outlet 2 of the water heating system 31, and a source outlet 47 that is connected to the inlet of the primary loop pump 15 as connections to the heat source side 56. The by-pass heat exchanger 25 includes a space inlet 49 for reheating water from the space heating system 33, 34 and a space outlet 48 for returning heated water to the space heating system 33, 34 as connections to the space heating system side 58. As shown by arrows in FIG. 2, working fluid directions are opposite with each other between the heat source side 56 and the space heating system side 58 in the by-pass heat exchanger 25.
The primary circulation pump 15 communicates with the source outlet 47 of the by-pass heat exchanger 25 and the water outlet fitting 22. The primary circulation pump 15 provides water head that is high enough to activate a flow sensor 54 for the water heating system 31.
The secondary circulation pump 16 communicates with the space inlet fitting 19 and the space inlet 49 of the by-pass heat exchanger 25. The secondary circulation pump 16 has a predetermined flow rate, which is determined depending on the space heating system 31.
The apparatus 32 has an air separator 10, an expansion tank 13 and a pressure regulator 12 for adjusting heated water pressure in space heating systems 33, 34 (refer to FIG. 3). The expansion tank 32 and the air separator 10 are provided between the space outlet 48 of the by-pass heat exchanger 25 and the space outlet fitting 20. The expansion tank 32 and the air separator 10 balance pressure and automatically eliminate air in water flows.
The apparatus 32 has a thermostatic mixing valve 17, which has an inlet that is connected to the space outlet 48, and another inlet that is connected to the space inlet fitting 19, and an outlet that is connected to the space outlet fitting 20 for supplying tempered hot water to the space heating system. As explained above, the space inlet fitting 19 is connected to the space heating return fitting 28 of the space heating system 33 or the space heating return fitting 30 of the space heating system 34. The space outlet fitting 20 is connected to the space heating system inlet fitting 27 of the space heating system 33 or to the space heating system inlet fitting 29 of the space heating system 34. The thermostatic mixing valve 17 keeps preset heated water supply temperature around 120° F. for the radiant space heating system or snow melting system 33 and above 140° F. for the forced air space heating system 34.
The apparatus 32 has the secondary circulation pump 16 between the space inlet fitting 19 and the space inlet 49 of the by-pass heat exchanger 25 for circulating heated media in closed loop for the space heating system 33, 34.
When temperature drops between the space outlet fitting 20 and the space inlet fitting 19 around 14° F.˜35° F. from the supply temperature depends on the space heating system 33, 34.
A house space heating thermostat 44 is connected to the control board 26 of the apparatus 32 for activating a space heating mode. When the space heating thermostat 44 is engaged to start, the control board 26 starts the secondary circulation pump 16, which circulates heated water through the space heating circuit. The temperature of circulated water is set around 110° F. for a radiant floor heating system and a snow melting system, around 180° F. for a base board heating system. The heated water supply temperature is set above 140° F. for a forced air space heating system. For the above space heating systems, the heated water temperature drops 14° F.˜35° F. from the supply temperature by design.
The domestic hot water capacity is from 2 GPM to 10 GPM depending on the input rate of the water heating system 31.
The operation of the invention is explained. If there is a request for domestic hot water supply through the domestic hot water outlet fitting 23, fresh cold water is supplied through the cold water inlet fitting 21. Immediately after the cold water supply, the priority device 8 communicates to the control board 26, and the control board 26 controls the three way valve 11 and the primary circulation pump 15 to change to a bypass mode in which the whole system is operated for providing domestic hot water to household plumbing fixtures. The three way valve 11 communicates with the water inlet fitting 24, the source inlet 46 of the by-pass heat exchanger 25, and the hot water outlet fitting 23.
If there is no request for domestic hot water supply, and a thermostat for house space heating sends request for heating, the whole system is operated only for space heating with closed loop system until domestic hot water supply is requested.
The room air temperature in the bypass mode may drop 2° F.˜10° F. from the room air temperature before the bypass mode is activated in about 20 minutes. The temperature drop depends on the heat insulation rate of the house.
The apparatus 32 of the present invention with the single water heating system 31 and the space heating systems 33, 34 can satisfy most of domestic hot water requirements for traditional household plumbing fixtures. The relationship between the input capacity and hot water flow rate is explained under the predetermined temperature of 120° F. for the anti-scalding device 9.
Basic Equation for apparatus 32 that produces hot water as is, and in case that the hot water temperature of the water heating system 31 is set above 120° F.
Input BTU×Efficiency (%)=500×GPM ×ΔT
Where

- Input BTU by BTU/hour
- ΔT=preset temperature—fresh cold water temperature
- GPM as gallons per minute

Actual GPM with 120° F. can be predicted with the following equation:
GH=(TM−TC)/(TH−TM)
Where

- GH: Gallon of hot water requirement for one gallon of cold water
- TM: Cold and hot water mixture temperature (The apparatus is set as TM=120° F.)
- TC: Fresh cold water temperature
- TH: Output hot water temperature in the water heating system

The input BTU may be changed depending on each house's domestic hot water requirement and/or space heating requirement.
While the invention has been shown and described with reference to different embodiments thereof, it will be appreciated by those skilled in the art that variations in form, detail, compositions and operation may be made without departing from the spirit and scope of the invention as defined by the accompanying claims.

Claims

1. A heated fluid distribution apparatus for a combined domestic hot water supply and space heating system, wherein the combined domestic hot water supply and space heating system comprises a water heating system and a space heating system, the apparatus comprising:

a) a cold water inlet fitting that is adapted to be connected to a fresh water source;

b) a hot water outlet fitting that is adapted to be connected to a house plumbing fixture;

c) a water outlet fitting that is adapted to communicate with an inlet of the water heating system;

d) a water inlet fitting that is adapted to communicate with an outlet of the water heating system;

e) a space inlet fitting that is adapted to communicate with a space heating system return fitting of the space heating system;

f) a space outlet fitting that is adapted to communicate with a space heating system inlet fitting of the space heating system; and

g) a by-pass heat exchanger that comprises a heat heat source side that is adapted to communicate with the water heating system, and a space heating system side that is adapted to communicate with the space heating system.

2. The apparatus of claim 1, further comprising a primary loop circulation pump, and a secondary circulation pump, wherein the heat source side of the by-pass heat exchanger comprises a source inlet that is adapted to communicate the water heating system, and a source outlet that is connected to the primary loop pump, wherein the space heating system side of the by-pass heat exchanger comprises a space inlet that is connected to the secondary loop pump for reheating water from the space heating system and a space outlet for returning heated water to the space heating system.

3. The apparatus of claim 2, wherein the working fluid directions are opposite with each other between the heat source side and the space heating system side in the by-pass heat exchanger.

4. The apparatus of claim 2, further comprising a priority device, a three way valve and a control board for prioritizing domestic hot water, wherein the priority device is connected to the control board, wherein the control board controls activation and deactivation of the three way valve, the primary circulation pump, and the secondary circulation pump.

5. The apparatus of claim 4, wherein the control board is adapted to communicate with a house room thermostat for turning on/off of the space heating system.

6. The apparatus of claim 4, wherein the three way valve communicates with the water inlet fitting, the source inlet of the by-pass heat exchanger, and the hot water outlet fitting.

7. The apparatus of claim 2, further comprising an expansion tank and an air separator between the space outlet of the by-pass heat exchanger and the space outlet fitting, wherein the expansion tank and the air separator balance pressure and automatically eliminate air in water flows.

8. The apparatus of claim 2, further comprising a thermostatic mixing valve, which communicates with the space outlet of the by-pass heat exchanger and the space inlet fitting, and comprises an outlet that is connected to the space outlet fitting.

9. The apparatus of claim 2, wherein the primary circulation pump communicates with the source outlet of the by-pass heat exchanger and the water outlet fitting.

10. The apparatus of claim 9, wherein the primary circulation pump provides water head that is high enough to activate a flow sensor for the water heating system.

11. The apparatus of claim 2, wherein the secondary circulation pump communicates with the space inlet fitting and the space inlet of the by-pass heat exchanger.

12. The apparatus of claim 11, wherein the secondary circulation pump has a predetermined flow rate, wherein the predetermined flow rate is determined depending on the space heating system.

13. The apparatus of claim 1, further comprising an anti-scalding valve, wherein the anti-scalding valve communicates with the cold water inlet fitting and the water inlet fitting and has an outlet that is connected to the hot water outlet fitting.

14. The apparatus of claim 13, wherein the temperature of water from the anti-scalding valve is set to about 120° F.

15. The apparatus of claim 1, further comprising a temperature and pressure gauge that indicates incoming hot water temperature from the outlet of the water heating system.

16. The apparatus of claim 1, further comprising a water check valve that prevents return water backflow to the cold water inlet fitting.

17. A combined domestic hot water supply and space heating system comprising:

a) a water heating system;

b) a space heating system; and

c) a heated fluid distribution apparatus;

wherein the heated fluid distribution apparatus comprises:

1) a cold water inlet fitting that is adapted to be connected to a fresh water source;

2) a hot water outlet fitting that is adapted to be connected to a house plumbing fixture;

3) a water outlet fitting that communicates with an inlet of the water heating system;

4) a water inlet fitting that communicates with an outlet of the water heating system;

5) a space inlet fitting that communicates with a space heating system return fitting of the space heating system; and

6) a space outlet fitting that communicates with a space heating system inlet fitting of the space heating system; and

7) a by-pass heat exchanger that comprises a heat heat source side that communicates with the water heating system, and a space heating system side that communicates with the space heating system.

18. The system of claim 17, wherein the heated fluid distribution apparatus further comprises a primary loop circulation pump, and a secondary circulation pump, wherein the heat source side of the by-pass heat exchanger comprises a source inlet that is adapted to communicate the water heating system, and a source outlet that is connected to the primary loop pump, wherein the space heating system side of the by-pass heat exchanger comprises a space inlet that is connected to the secondary loop pump for reheating water from the space heating system and a space outlet for returning heated water to the space heating system.

19. The system of claim 17, wherein the water heating system is an on demand flow through tankless water heater.

20. The system of claim 17, wherein the water heating system is a fully modulating device, which can supply hot water at a predetermined temperature ranging from about 100° F. to about 180° F.