Tankless with varying incoming pressure from well tank/pump?

[rick.a]

OK, it's done. I have installed the tankless (several weeks ago) and have used it long enough to report back to everyone.

I have a Rinnai 53i and this unit just fit into the tight vertical clearance in my crawlspace. I got this specific model because of it's low vertical requirement. Space consideration was the #1 reason for switching to the tankless.

Propane company did the gas part of the install. I did the plumbing. Very straight forward, especially since I redid all the plumbing in the house as part of a bath remodel.

The 30-50 water pressure fluctuation from my well pump/tank system does not seem to make any difference. It works fine. We experience about a 10-15 second additional wait for hot water, and this is acceptable. Flow rate is fine (but the incoming water temp is warmer this time of year). We don't like the cold water sandwich and don't like it when the hot cuts off when the flow is too low. We hand wash dishes. I may install a small electric "buffer" tank downstream of the Rinnai which should solve those issues.

By the way, does anyone know what the hit may be in flow rate/pressure if I install a sediment filter (just after the well tank)? I fear sediment buildup in the heater since it may be prone to plugging up. I installed a 10" cartridge housing but have not yet put the filter into it yet. If I use a 30 micron filter will it block much flow? By the way our water is crystal clear and no sediment is showing in the clear empty housing. Might this mean that I don't even need a filter, or is this false logic and small particles are flowing through?

thanks,
Rick

[ballvalve]

My well water could be bottled, but the electric elements build up huge deposits of calcium that hinder their operation unless they break off and drop to the bottom of the standard tank unit. Which they do if using a HIGH watt density element.

If I had a tankless, I would spend hours a year filling it with lime away and trying to get a brush throught it to remove the lining that makes the efficiency about 1/2 of advertised.

tankless are foolish when the best is a $200 tank that has only 2 or three parts and sit on every shelf in America. Many life cycle cost tests prove it.

Sediment filters dont help with dissolved solids which tankless units like to extract.

[LLigetfa]

My well water could be bottled...

Ja, mine too, as mineral water! Despite having both an iron filter and water softener, I still see a lot of mineral buildup on my fixtures.

[rick.a]

Well in that case, I should be fine. The tested hardness level in our water is very low. We also have never seen any buildup at any fixture.

But I still would like to know how much pressure we would loose if I install a 30µ cartridge filter. Or for that matter is it just a waste of time to use such a filter.

[DonL]

Like BallValve said; "Sediment filters dont help with dissolved solids."

You would just have put a filter in it and see what you get.

The flow rate changes as it gets plugged up.


DonL

[jadnashua]

Any filter acts as a restrictor, and it gets worse, as mentioned, when it starts to actually collect debris in the filter media. Now, how restrictive depends on the size and design of the filter and the filter housing, which should be stated in the specifications. It will have some nominal pressure drop across it that will increase as it fills up. It isn't a bad idea to plumb pressure gauges on the inlet and outlet, as they will give a good indication (while there is a flow) of how plugged the filter is without having to take it apart to look (which may not tell you much). Note, with no flow, the gauges (should) read the same on the inlet and outlets...it only changes while there is flow.

[ballvalve]

I DO use filters in order to save getting junk in fixtures. Usually 5 or 10 Micron.

[master plumber mark]

i think I would be more worried about the incomming pressure
and when the well kicks on ....

how hard is the water anyway... they claim you need a water softener if you have more than 11 parts hard water...

good luck with this one