electronic flow valve

does anybody know of anybody who makes an electronic flow valve that sences water flow. what i want to do is put an electronic flow valve in my dhw water line so as soon as we use the hot water it will start to stoke the stoker on my boiler.hopefully it will cut down on my lag time of the fire raming up to maintain my dhw.

chris

May I suggest Chris that this idea is too darn complicated, expensive, and less than fault tolerant for home use.

Ill suggest something cheep and complicated -- safer


Buy a larger electric water heater. Don't wire it up just place it in line before your current heater for a buffer tank. Now circulate both tanks with a bronze pump off each output port - ( place a valve to slightly restrict flow to the pump from the primary) into your plate exchanger or DHW boiler leg. With a strap on Honeywell strap on stat on both outputs of each tank to start and stop the one circulator. Set the stat on the primary tank to switch off at 120 and the buffer tank to switch off the pump at 110. Simply accept the built in differential for close on temperature drop. Wire in parallel to control the pump. The stat on the buffer will control the launch - the one on the primary will control the halt.

In this arrangement you get reservoir of hot water (the primary tank) to use before the boiler is called to service by cool output of the buffer tank - exciting the bronze pump and beginning the charging cycle -

This all happens in about the same time frame as your current system --- but you still have DHW service from the primary heater as the process begins postponing your need for heat DHW heat from a boiler that is ramping up to meet the demand.

Another feature and benefit is if you can circulate the DHW in your home system -- then you have almost instant hot at the lift of any hot water faucet - and its safe temp because circulation stops at 120 - stopping water temps of the DHW that can build above 120 from a boiler idling and a min of 140 --- water above 125 is not safe to use at a faucet.

Ooooh, this is a good one!!!! Scott

Chris

There are lots of flow switches on the market, the trick is finding one that senses at a low enough flow rate. if you search on Ebay for flow switch, you'll get lots of hits.

I'm not sure that I would reccomend using DHW water flow as a primary control for the stoker motor, the stoker should be under control of the aquastat. A continuous flow on the DHW could overstoke the fire if there isn't some means to limit it.

You might be able to use this flow signal to acutate a timer of some kind that would run the stoker for a predetermined amount of time, giving you a headstart on building up the fire.

The buffer tank approach is not a bad idea either. You could use the tank thermostats to run a small circulator pump that would shut off when the tank reached a preset temp.

Bill

stokerscot wrote:Ooooh, this is a good one!!!! Scott

I am waiting with my flame suit at ready!

I figured you were hunting Scott

The next step is to heat the buffer tank with a solar panel

Thats my later this summer home improvement project - but mentioning solar when cheep coal is still available is like bragging about your new rice grinder on a American bike page. Don't ask!

A common arrangement with solar is to have an electric main tank and to simply heat only the buffer tank. Either way you will need a tempering valve and a circulating pump

Pull another zone to an insulated boiler mate tank and lose the coil, the boiler will respond on a call for heat and you will have a ton of HW stored, end of problem. It also eliminates any scalding concerns in the event the boiler goes over temp.

Cheap, works best, safest.

or install a 1000.00 boiler mate

OK, lets compare total costs for parts..

From your description we need two honeywell strap-on aquastats,,
we need an electric hot water heater [cheaper than a storage tank] for the buffer tank
and We need two Bronze circulators...

Can you supply the prices [retail] for the above shopping list??? I think they are about equal... to the $1000 indirect hot water heater?

BUT I would think that with some patience and shopping ebay, everything but the buffer-tank could be bought at wholesale or below...

How about a real clear diagram, for the pump [s], wiring circuit[s] and the priority of the aquastats..

Describe it like you are writting 'Plumbing for Dummies' I've only plumbed 6 new houses [with hot water baseboard] and retrofitted 3 boiler systems with new boilers... so your description above is a bit confusing to my 'inexperienced mind'...

Greg L

pm SENT

Only one bronze pump required. They aren't too much more expensive that the circulator necessary (usually included) for a boiler mate.

What is this lag time like?

I've just purchased a KAA-2 but I've not installed it yet. So I'll probably have the same issue. I have no electric water heater.

Maybe a pressure switch on the hot water line that trips a timer that would run the stoker motor for a short time?

The time lag will be a "moving target"

It will depend on the differential setting of both appliances and where each is in that bell curve or the fire/heating/idle cycle.

In my primary/buffer DHW tank contraption and the two aquastat controls, I significantly widen the bell curve on the call end and HOPE that the anticipation is enough to carry the load over the morning demand. If not I could widen the curve by turning down the buffer tank control, but in my case (and each load is different) the spread I outlined works well!

Rather than waste bandwidth - if you want more info please PM as Greg did. It easier to address specific applications than it is to write a book encompassing everything anyone could want to know about everything. I know Greg thats what you would like - its just not me!

Sting wrote:Rather than waste bandwidth - if you want more info please PM as Greg did. It easier to address specific applications than it is to write a book encompassing everything anyone could want to know about everything. I know Greg thats what you would like - its just not me!

Actually this is why I incorporated the KB, for information like this. Instead of writing it and seeing it get buried it can all be in one concise article. I added a new one for hot water coils with a brief explanation and diagram for a thermal siphon.

Anybody needs any images made let me know. I'll replace the current one with a few 3-D images for better visualization.

Feel free to add anything you want: http://nepacrossroads.com/kb/Hot_Water_Coil