heating system simply wont keep up

Jim Hall

I will work on that. Thanks

Jim Hall

walls are isolated from slab by 2" blue rigid foam
water heater element is drawing 4400 watts when checked with meter. I did turn temp down on water heater to about 110 degrees. we will see if water heater will recover.

hr

Sounds like the pump, isn't

the temperature you are reading could be conduction transfer. Ideally the pump would have shut off valves on both sides to allow you to remove it and see if the impeller spins when powered. If the pump got dropped along the way that will usually break the ceramic shaft. Motor spins, but not the imeller ;(

It is also nice to have a valve on each loop to allow you to purge loops one at a time. I've cheated this by using a Vice Grip pinch off pliers to close loops off.

You should have plenty of btu's from a 4500 w heater to warm a well insulated basement space of 1200 square feet. If 4.5 K won't do it I doubt a 5500W element would make a difference.

You can run both elements together if you install another stat like the top one, and feed the bottom element with another 30 A circuit. That wiring is usually shown in the manual that comes with the heater. You can buy tanks wired like that also.

hot rod

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S Ebels

I agree

From my post above;

"The water heater not shutting off and the small temperature difference supply/return don't add up to me. Something else is going on."

Jim Hall

noticed grundfos pump is installed horizontally instead of vertically. Reading pump installation an it looks questionable as to weather it will work. Pump sounds like its working and gets a little warm. both ends of loop are near 90 degrees so wouldn't that tell you the pump is working. If supply was 90 and return end of loop was ice cold, wouldn't that tell you that its not pumping?

Jim Hall

I am not really wanting to run both elements if I don't have to. The reason I installed this system was for energy efficiency and if it takes 8800 watts running continuously to heat floor then I'm not sure how efficient that would be.

Timco

As long as the pump motor's center axis is horizontal, it is OK. Never vertical. It can pump Horizontally or vertically, just the motor axis matters.

Tim

Jim Hall

how can you tell by looking at pump?

Timco

Not sure how else to explain it...motor axis (centerline of the pump) needs to be horizontal. The circle or end of the pump must be to the side...never up or down or at an angle.

Tim

Gordy

Floor coverings

Is there any high r value floor coverings?

Go out and buy a cheap 50 dollar infra red thermometer. You can use that thermometer across the floor to see if all loops are heating, hold it close to the floor couple inches. This handy little tool should help you immensly in trouble shooting your system.

Sounds like you have air in the loops. Your manifold set up is not the best to purge the loops with out individual purge / isolation valves on each loop.

Gordy

Jim Hall

if loops had air wouldn't water heater recover or not because it's not recovering now. I will check both elements in water heater tomorrow.

Ericjeeper

wow

I am no expert, but I do have a similar system. I would think with such a low delta T ,The pump needs slowed down just a bit.But that is going to put more load on the water heater.
As the return temps will be lower yet.
I agree go buy a laser temp reader.I bought one just for my floor. I can pinpoint the tubing with mine by noticing the differences in temp as I scan the floor surface.
You are going to have to figure out what is keeping that one loop from flowing.Like HotRod said. clamp off the other three loops with visegrips on the supply side.see if you can force purge the other loop.
I heat my house with temps around 85-95 degrees.
Pictures will be a big help.

you get this group of men a few photos of the system, and I guarantee they will figure it out.Many have helped me over the past few years. Hotrod,Rob, Mark, Bob and many more..

Ray Landry_2

How about the possibility of a system leak? Was the system pressure tested prior to being filled with water? You could be brining on fresh cold water so much that the heater cannont recover. With no guages it's tough to know what your static pressure is. Is the make up water turned on or off?

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Chris_82

We used to try this

Take a well insulated throw rug or coat 3' x 3', put any thermometer under the rug, put the rug or coat on top and wait 1/2 hour or so with out disturbing the rug/coat, and then read the thermometer, what is the temp? This is a good way to trap the radient energy to see if it is there in the first place. If when you take the cover off, so to speak and the temp is up , you might have a heat loss problem, if the temp is not there back to point one.

mikea23

DO THE MATH

Mark Wolff_2

not always true

That depends on your wiring arrangement. If you have the proper circuit breakers installed @ the electrical panel, you can rewire the elements for both on per factory diagrams.

Just because it doesn't always happen doesn't mean it can't or shouldn't.

Jim Hall

make up water is off.

Jim Hall

heating system not keeping up-- picture

Here is a picture of radiant heating system. 1 zone, 1 pump, approx 1200 sq. ft. slab 10' below grade. 80 gallon electric water heater. 4 loops of 250'/ loop. Supply temp guage says about 90 degrees, return temp guage says 85 degrees. Water heater running 24/7. 400 sq ft of space is an exercise room with laminate wood flooring on top. 800 sq ft of space is a racquetball court with 2x4 sleepers on top of slab then 3/4" wood floor. Closed system with micro bubler installed and backflow prevention installed. Unfortunately, no seperate zone shut off or purge valves installed and no pressure guage on either supply or return. Also, 1 of 4 loops is cold at supply manifold and at return manifold. Slab insulated with 2" blue polystyrene,wire mat, 1/2" pex tubing, then 3-4" concrete.Any help will be much appreciated.

Steve_35

Quick heat loss

with a design of -20, R10 walls, R38 ceiling, no windows or doors 30' x 40' shows a loss of about 8,000 btuh. So the water heater has plenty of capacity if the above info is correct.

Put an ammeter on the supply to the water heater. Double check the wiring at the t-stat. Make sure both elements are getting 240v when they should be. If the water temp is really under 100F only the top element should be firing.

Make sure you're pulling off the hot side and that the dip tube is in place if your return is on the cold which is how mine is set up.

The deltaT is WAY low for a 250' loop in concrete. I'd say the water is moving too fast.

My remote guess is if the water heater really isn't keeping up you have a problem with the water heater. Mis-wired, bad element, bad t-stat, bottom element only firing. Once you monitor the amp draw and the voltage for a bit I suspect you'll figure it out.

Gordy

No pic

No pic Jim ! Also how do you know the water heater has benn running 24/7. No sleep?

Jim Hall

Sorry had to have it resized, was too big to view. . Thx for being patient!

Gordy

Well

Purge, and shut off valves should be easy to install.

Again are you sure the water heater is running 24/7?

Which loop is cold?

Did you do this installation!

Gordy

Ericjeeper

thats a start

He has a few things going there.. I see the pump plugged into a 120 volt recep. is that on a stat? He has the left lines coming out of the floor marked"supply" and left return
if so he is not pumping away from the expansion tank.which would work best.. Maybe he is pumping away and trying to heat through the returns.
If the loops were laid out properly the supply would start along the outdside walls and work their way in.
You really needa pressure guage.. Go buy a female garden hose adapter to get back to pipe threads and add a low pressure guage screw something together temporarily attach it to the drain valve on the water heater and open the valve. see whats going on here. I do not see any place simpler to attach a valve.


if the system was mine I would change the return to the bottom of the tank. Just remove the drainvalve add a Tee and then put the drainvalve back in.Then cap off the return on the top of the tank.

Jim Hall

3rd loop from left is cold at supply manifold and cold at return manifold system seems to be running 24/7 because supply temp never gets higher than around 90 to 95 degrees but water heater stat is set to 125 degrees.

Jim Hall

thanks for help I have a 120 volt stat which breaks power to outlet pump is plugged into. Bottom manifold in picture is supply and top manifold in picture is return with pump pulling return back to cold top of water heater.

Tony_23

\"do over\"

You need balancing and purge valve(s).

Repipe the return to the drain tap or replace the poly dip tube with a copper one.

If one loop is cold, that could be an issue with capacity of the floor to keep up with the space. The other issue is your sleeper floor over the concrete. It makes a good insulator to keep the pad warm and the room not.

Gordy

Okay

The aquastat on a water heater can vary 20* or more, and be very erratic shooting over or under that 125* setting some what.

Could be this thing happens to be cycling off while you are in bed. Have you tried to turn the aquastat down or up, to see if it cycles on and off? I think the main issue is the cold loop.

Does the pump have an aquastat also or is it just running 24/7? If it does it probably has a 15* differential.

Gordy

Ericjeeper

Is there a perimeter drain around the house?

Or a sump pump inside the basement? Could the water table be high? Ground water wicking heat away from the slab? This does not make any sense.. I heat 3200 square feet using a water heater..and solar supplement.. Even if the pump is greatly oversized.. The hot water is in the pipes..a cold slab will suck the heat out of it..eventually.

Ted_9

o2 barrier

Is that aqua pex? does it have an 02 barrier? It looks like Watts aqua pex. If you said this already, please forgive me.

If there is no O2 barrier, then you shouldnt have any cast iron parts.

Massachusetts

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hr

Looks like 3/4 pex?

it takes a lot of flow to purge all those loops at one time something along the lines of a swimming pool pump :)I doubt your water system has enough pressure to purge all those loops at once.

Add the individual shut offs on either manifold, and a nice full port purge cock.

A flow meter or a pressure gauge on both sides of the circ would tell you the amount of flow you are ACTUALLY moving.

Sometimes too simple can backfire and cost a lot of time and frustration. Adding a few more components would make it easy to start, troubleshoot, balance and repair if necessary.

hot rod

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Mark Wolff_2

Mark Wolff_2

Still Missing The Point

Jim, sorry that this thread is taking so long to answer your question.

Hot Rod is right. The first challenge you have is that one of the loops is air locked. The only way to fix that is to cut in some isolation valves and boiler drains on each loop, or at least individual isolation valves, with a boiler drain on the main and an isolation valve just past it to allow for individual loop purging.

Your room will not heat no matter what without that fixed, because 25% of your heat supply is missing.

The second potential challenge is something that was already mentioned but got buried in the thread. You could have a problem with the supply and return being tied into the top of the water heater. It is probably going right from the return back to the supply, (I assume you took the sparge tube out of the water heater?) This doesn't allow a full cycle of time for heating as it would with a proper sparge tube installed, or entering from the bottom.

If that is not the issue, or even if it is, the third challenge that should be addressed is the flow rate in the system. For such a low delta T (difference between supply and return temperature) it indicates you have your pump speed a little fast for the system. Restricting the flow in the system through a smaller pump, a balancing or ball valve, or reinstalling a missing sparge tube will fix this challenge.

Also, the reason the water heater is not fully heating is due to the single element trying to keep the unit hot. The load on your system (1200 sq. ft. sub-grade) is slightly more than the 4500 watt element will be able to handle on it's own when your outside temp is this low. If you look at the paperwork that came with the water heater, it will show you how to re-wire the upper aquastat control of the water heater to allow for 2 element heating with both operating at the same time. This will be needed in your case, due to the size of your system and the heating demand on it.

Your system will not always need the extra heat from the second element to keep up, but with it wired in parallel you will find you don't have any more issues with the temp. It will start to cycle like you want.

This should help you out.

Alex Giacomuzzi

Safety ---- Back Flow Preventer...

Jim:
Your pictures do not show a back flow preventer. They show a check valve. I understand you have a closed valve ahead of the check valve with food grade antifreeze in your system. I would suggest you install a proper back flow preventer in this application along with the suggested 30 PSI pressure safety valve.

In one of your posts, after mentioning that the system had run a number of days, you mentioned the floor was warm. Can you share what temp the floor was at??

Insulation has been discussed in this post below and on the sides of the slab, can you tell us is there is much of any air leakage around your windows, doors, or other openings? Is the construction complete in the area or n the house? If this were to be the case-- air leakage, it would have a huge affect on room temperature.

Regards Alex

Dave Belisle

PURGE ! PURGE ! PURGE !!

You need to purge that system and you can't do it the way it is set up now.

Put some strut on the bottom piece of plywood. Pick up 4 threaded brass tees. 4 ball valves ,4 brass nipples , 4 boiler drains , 4 strut clips , and 8 PEX adapters. That way you don't need to get your torch out ....

Purge each line individually and you will be surprised how much air will come out of that system.

Other issues that have been mentioned.

Without a oxygen barrier you can not use any Ferris metal components, The circulator and flanges need to be replaced at sometime with bronze.

The circulator on a cord is fine as the National electrical code allows fractional HP motors to be disconnected with a cord, but if the water heater is not within site on the power panel it needs a disconnect.

You need a backflow on the feed , not just a swing check.
Something like a Watts 9D.

Be careful rewiring the water heater. It is a UL approved unit and will loose the rating when rewired......

Things you should do...........

1, Install purge valves, you should have heat.

2, Install a backflow to protect yourself and your families domestic water supply.

3, Add a disconnect to safely work on the heater if the panel is not near by.

4, Know the circulator isn't going to have a long life.

With 1,200 feet of PEX , and 15,000 BTU you should be good to go , enjoy the heat.......



Dave in NH

Jim Hall

thanks dave! I will do as you suggest I am working on getting a pressure guage set up on the drain of water heater to see what pressure is in system. how much water should I expect to come out when I cut pex tubing? Also, I will install pressure guages and shut off valves on both sides of pump and repipe return to bottom drain of water heater. FYI service is within sight of water heater about 5 feet from picture.

Larry Weingarten

assumptions

Seems there are some assumptions that need verifying. Is the water heater really heating 24 hours a day? There are clocks that will tell you. What direction is the pump really pumping? If backwards, it could cause problems. Have you verified the thermometers by actually touching the pipes? They could be off. Is there any chance a loop got tied back into the wrong manifold? Good valving will let you prove correct piping. Hope that helps.

Yours, Larry

Chris_82

Ditto the balancing & purge valves, should be the first thing he does, can be spliced into pex. ONE small bubble and that arangment won't circulate. 2x4 sleepers perhaps not the best idea, but will eventually heat up, but the word eventually is going to be highly debatable, sorry but heating under raised floors needs to be thought about well in advance. This might sound a little bizzare but any way to place, push or stick more tubing under that raised floor? you have created a radient trap with a very good insulator...air.

Jim Hall

installed a pressure guage on water heater drain. 45 psi so I drained water from system now its at 14 psi. What psi would be optimum for a closed system? Tried to pinch off other loops to get cold loop flowing but nothing yet. Is it better to install shut off valves and purge valves on return or supply lines or does it really matter?

Brad White_153

Closed system pressure

Pressure in a closed system depends on elevation. You want at least 4-5 PSIG at the top of the system plus one PSIG for every 2.31 feet of elevation.

If your system is ten feet high:

10/2.31 = 4.33 PSIG + 4 to 5 PSIG topping pressure = 8.33 to 9.33 PSIG bottom pressure.

These are minimums but anything 12-14 is OK for what I gather your system height is. You just want to make sure that your relief valve setting is not approached during hottest temperatures (meaning have sufficient expansion tank capacity).

Jim Hall

its vanguard pex and I don't beleive its o2 barrier stuff. Will plan on pump not lasting as long. Not sure why my plumber installed this but its in and no shut off valves on either side for servicing.bummer.