While in the shower if someone flushes the toilet you get cooler water for a few seconds then it goes back to normal. My house is two years old and it did start happening until I had a second hot water tank installed for my in floor heat. I understand that what normally happens with older systems is you get hotter water if someone was to flush the toilet.

I could go on and on about other things I think is wrong because my in floor heat does not get as hot as other systems I have seen but 3 plumbers have been over including the idiot that installed it and none of them can figure out why this is happening.

Tank 1 is for the house the hot goes to a manifold and the cold is joined to the cold of tank 2 as well to a manifold for the house. Hot from tank 2 only supplies hot water for the floor.
From out side the city water comes in through the meter then through a check valve up though a T to the cold water house manifold at the T the water goes through another check valve then into both tanks. I'm not sure why the second T is there and I wonder if if isn't causing the issue.

I have pictures of the system if anyone would like to see the plumbing. If you can figure this out you should be called a MASTER plumber because everyone else just scratches their head.
Thank you

Actually, if the house is only two years old, then you have pressure balanced valves installed in the tubs and showers.

These are designed specifically to avoid being scalded when some unthinking idjit flushes a toilet when you're in the shower.

Quote:

---

Originally Posted by iamgrowler

Actually, if the house is only two years old, then you have pressure balanced valves installed in the tubs and showers.

These are designed specifically to avoid being scalded when some unthinking idjit flushes a toilet when you're in the shower.

---

Ok I understand that, any idea about why the cold water comes in over top of the hot when a toilet flushes. I question the second check valve but I am not a plumber.

The second tee and check valve are to prevent the hot water in the hydronic heating loop from re-entering the cold water system -- If it wasn't there, the hot water, which is under greater pressure from thermal expansion would seek the path of least resistance, which is the lower pressured cold water side.

Did the Plumber install a expansion tank when he installed the second tank?

If he didn't, then he needs to come back and finish the job.

The first check valve is likely mandated by code as a means of preventing water from your house (contaminated) from re-entering the public source (uncontaminated).

Yes the second plumber installed an expansion tank.

The second check valve is only on the hot water sidebefore the cold water goes to either tank.

I have pictures if would would be easier to see a visual.

Other problems that have occurred since the second tank was put in is when my wife was running a bath ran out of hot water before the tub was full. No other water had been used for at least an hour before.
Both tanks are 40gal.

I am so frustrated with this system I want to rip it out and start again but that is not feasible.
Thanks for the replies.

Quote:

---

Originally Posted by shotclock

I have pictures if would would be easier to see a visual.

---

A photo would be helpful.

If you can, label which line is which (Domestic Hot/Cold and Hydronic)

I will try to label them. What does hydronic mean?

Can the pictures be posted here or do we need to email them.