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Quotes - Engineering - SalesDomestic Water Heating
Potable Water and Instantaneous Heating
Domestic hot water duty uses plate exchangers for instantaneous and semi-instantaneous heating from boiler water, district heat or recovered condenser heat.
Double-wall construction. Where a non-potable fluid heats potable water, double-wall plates put a vented gap in the leak path so a breach appears outside the unit. Many jurisdictions require it and it is worth confirming rather than assuming.
Instantaneous means control. Domestic hot water demand is spiky, and an exchanger sized on peak flow can be badly controlled at trickle flow. Control valve sizing and turndown belong in the same conversation as the exchanger.
Scaling. Hard water scales at the hot surface. Lowering the medium temperature and adding surface reduces scaling rate substantially, and a frame that opens makes descaling a routine job.
Typical Specification
- Application: Instantaneous and semi-instantaneous domestic hot water
- Construction: Double-wall plates where required for potable duty
- Heat source: Boiler water, district heat, recovered condenser heat
- Control: Turndown and valve sizing designed with the exchanger
- Scaling: Reduced by lower medium temperature and more surface
- Cleaning: Frame opens for descaling
- Materials: 316 stainless standard
- Regulatory: Confirm double-wall requirement with the authority
- Small duties: Brazed plate where a frame is not warranted
- Recovery: Condenser heat recovery as a pre-heat stage
Common FAQs
Where a non-potable fluid heats potable water, many jurisdictions require it. Confirm with the authority having jurisdiction, because requirements vary, and specify it at purchase rather than discovering it at inspection.
Usually control rather than the exchanger. Domestic demand is spiky, and a control valve sized for peak flow behaves badly at trickle flow. Turndown belongs in the design conversation.
Lower the medium temperature and add surface area, which reduces the wall temperature where scale forms. A frame that opens then makes periodic descaling a routine task rather than a project.
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