Tankless Water Heater

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    • #278289
      Avatar photoIan Wilson

        We want to replace our standard gas water heater with a tankless one. Our house is pier and beam – can we put the tankless under the house? I realize it would have to be mounted on some 2×4″s. Has anyone ever done this? The unit we’re looking at is a Takagi. It needs 6″ under it for the fittings and then stands 20″ high. The pipes run 6′ below the subfloor. So they’d have to be routed down and then up into the unit. It also doesn’t get very cold here (rarely below the 15 degree minimum). We could also surround the unit with a wind chill breaker wooden box. If it’s below the floor, would it require any other venting? A vent out the side of the skirting?
        Thanks for any help,
        Catherine Tucek

      • #298194
        Avatar photonicktheplumber

          Most of the instantaneous water heaters in the US use gas, but a few are electric. The gas heaters MUST be vented. If yours is gas, refer to the manufacturer’s specs for details. You can install your unit in the crawlspace, just so long as you can route gas and water pipes to it and vent it properly from where you locate it.
          If it’s gas fired, you must also provide adequate fresh air ventilation(e.g. you can’t place it in an unventilated closet). I’ve installed a few of these units and they can save on energy costs. The main concern (after installing them properly) is that some of these units have very low flow rates. Make sure that you unit has a flow rate adequate to meet the maximum simultaneous fixture demands of the dwelling.

          As regards protecting the unit from cold smbient temperatures, this would only be a concern if your air temperature dips below freezing. You should realize also that these units are rated as to their “temperature differential.” This is the number of degrees that they can increase the inlet water temperature while providing hot water at an adequate flow rate. If you want hot water at 120 degrees Fahrenheit and the unit is capable of a 70 degree differential, the inlet water should be no colder than 50 degrees…


        • #298195
          Avatar photoSelgas

            Most Tankless units (continuous flow heaters) are also powered with electricity to drive the fan and combustion controls. As they are connected to a power supply and a gas supply they are designed by their very nature to deliver water at a set temperature at the delivery point. The flow of water available is dependant upon the temperature you have selected for the machine to supply water at the outlet. They are all rated at giving a certain flow over a certain temperature rise and as a consequence to this the hotter the temperature you select the slower the flow will be (once above showering temperature) to achieve the desired temperature required.
            Select a size that will provide you with the required flow at the desired temperature you want.
            Nick has answered the installation specifications for your area and I will refrain from adding to them as they differ greatly from Country to Country – down here we have fitted many hundreds of them for very satisfied customers.
            But like the women always say size is important – the right one for the right job = a happy customer.

            Selgas Services Ltd
            Craftsman Gasfitters, Plumbers, Electrical Service Technicians

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