Plumbing query - hot water tank

aoifski

I'm not sure if there's a specific forum dedicated to plumbing - if there is feel free to redirect me!

I live in a detached house which was built by a contracter who hired a plumber for us and basically every issue we have had with the house has been plumbing related! Disaster!

Anyway the lastest saga is that we have the boiler (gas from a gas tank powered) on for about an hour in the morning and an hour in the evening and the water is luke warm only. Central heating is underfloor and is currently off so the boiler is only powering hot water to the tank and a couple of rads at the moment - so no major drain on the hot water coming from the boiler.

My understanding of plumbing - which is rudimentary and gained from quizzing whatever plumbers have come to the house to fix various issues! - is that the boiler heats the hot water which travels through the pipes to whatever it's supposed to be heating and water which is in the system is travelling back to the boiler (the return system).

Currently the flow pipe from the boiler is roasting. After the boiler has been on for a while the return pipe is also roasting, as are the rads....and yet no roasting water in the taps! Why is no hot water going to the tank and why is it returning to the boiler without filling the tank with roasting water??

There are 3 pipes in the water tank (this is for my own info)...I guess the one coming out of the top is the hot water feed directly to the taps. There are 2 pipes down at the bottom. The higher one of these is the hot water coming in from the boiler. What's the lower one? A return pipe? And if this is hot also but there's no hot water coming out of the top of the tank where is my issue likely to be? An airlock somewhere?

thanks to anyone who can get through my epic and help!!

aoife

I would try from cold, turn on your boiler feel the pipe going to the side of the cylinder on the top, you should feel heat there quite quickly, it should then go around a coil inside the cylinder which transfers the heat to the cylinder, if the flow of heat from the boiler to the cylinder is right you should have hot water in about 30 Min's, feel the top of the cylinder if this isn't getting hot then although you have heat to the top and bottom pipes it insufficient to heat your cylinder, you may want to look to see if you have a two port fitted on the pipes normally near to the cylinder from the boiler, this controls the flow to the cylinder and at times can fail to open, it Will have a small arm on the side to allow you to manually open the valve, good luck, Gary.

Micky Dolenz

another thing worth checking is the return pipe from the cylinder. There should be a valve there to turn down flow of water through the cylinder coil. It could have a red wheel handle, turn turning it like you would a tap to open, this may improve the heat up. The valve shouldn't be opened all the way as it may affect the balance (equal distribution of hot heating water)in the heating system.

2 stroke

You should have at least 4 pipes attached to the cylinder. Hot water to taps from top, cold inlet feed at bottom, (often at back of the cylinder) and flow and return to boiler (usualy on same side of cylinder one above the other).
The water from the boiler does not mix with the water in the cylinder, but exchanges its heat as it travels through coil of pipe inside the cylinder.
Sounds like your system needs to be balanced/timers/thermostats checked. either that or you may have a hot water leak.

aoifski

Thanks 2 stroke and everyone else for comments. I will check the valve on the return pipe.

Re the flow and return pipes 2 stroke, if the flow is hot and boiler on, am I right in thinking the return pipe should only be hot if the tank is full of hot water??

And if return pipe is hot and tank not full of hot water, something is wrong somewhere inside the tank??

2 stroke wrote: »

You should have at least 4 pipes attached to the cylinder. Hot water to taps from top, cold inlet feed at bottom, (often at back of the cylinder) and flow and return to boiler (usualy on same side of cylinder one above the other).
The water from the boiler does not mix with the water in the cylinder, but exchanges its heat as it travels through coil of pipe inside the cylinder.
Sounds like your system needs to be balanced/timers/thermostats checked. either that or you may have a hot water leak.

JamesM

aoifski wrote: »

Thanks 2 stroke and everyone else for comments. I will check the valve on the return pipe.

Re the flow and return pipes 2 stroke, if the flow is hot and boiler on, am I right in thinking the return pipe should only be hot if the tank is full of hot water??

And if return pipe is hot and tank not full of hot water, something is wrong somewhere inside the tank??

If you have a cold cylinder, it will take quite a while to heat the water in the cylinder. The flow will get really hot as soon as the boiler has heated up. The return will take a bit longer, because the coil in the cylinder is heating the surrounding water. But, if the circulation is good, the return will be very hot quite a while before the water in the cylinder is hot enough for a shower. I think that it would take well over an hour before you would have enough for a bath.
Jim.

caspermccormack

I think you have a miss understanding how the hot cylinder works, The boiler does not directly heat the volume of water in the cylinder, it is routed through a coil( hot flow on top and cold return on the bottom).

The return can become hot very quickly if the pump is powerful enough but that does not mean that the water in the tank will be at the same temp.
Do you know the size of the tank that was fitted, is it insulated?. Its harder to heat if the water is quite cold. Even if the water was tepid it would heat much quicker.

Hope this helps