OFCH heating tank in attic

Evenidonhnaill

I noticed recently that water was coming out of the over flow in my attic and I got a plumber in thinking it may have been an issue with the ballcock in the tank not that i know anything about heating systems. The issue seams to be more complex, while the plumber checked the tank he noticed that the water was hot not cold like it should be. it seams that when my heating is on its heating the water in the tank like and extra radiator! He also after looking for a cause couldn't find the reason for it.
Im concerned for a number of reasons for example what if the hot water melts the tank, the extra cost of heating my attic which i can afford and how to fix it without costing me a fortune.
was wondering if anyone else had a similar issue and can tell me the cause and how they fixed it.
One suggestion was to change the open system to closed but to be honest I haven't a clue what that means.
Any insight would be appreciated.

dazed+confused

Is your immersion heater on when this happens? The pressure relief from the hot water cylinder could be boiling over and into the tank. Hard to tell without seeing it though. You can't just convert from open to closed without making a lot of modifications, so get an expert in.

Evenidonhnaill

It happens when the heating is on. The heating heats the water in the tank and in the radiators. I know the panel for heating has the option for hot water only and heating only but in reality if heating is on it heats water in tank and radiators plus the tank in the attic which should not be happening. The plumber i had out was completely stumped by what was causing it but said it must of been going on for a long time. He suggested in the short term if having heating on to put the thermostat to the highest setting and switching the heating off before it reaches it.

Would changing to a closed system actually solve the problem though?

I want to try get it sorted before the winter as don't want to be throwing money away heating my attic space as effectively the tank is working like an extra radiator atm or so the plumber said.

Wearb

dazed+confused wrote: »

Is your immersion heater on when this happens? The pressure relief from the hot water cylinder could be boiling over and into the tank. Hard to tell without seeing it though. You can't just convert from open to closed without making a lot of modifications, so get an expert in.

Unless it's the bigger tank in the attic, it's unlikely to be caused by an immersion problem.
Most likely bad plumbing, often caused by later addons like a boiler stove etc. depending on your setup, a sealed system might be best solution.

Evenidonhnaill

Wearb wrote: »

Unless it's the bigger tank in the attic, it's unlikely to be caused by an immersion problem.
Most likely bad plumbing, often caused by later addons like a boiler stove etc. depending on your setup, a sealed system might be best solution.

There isn't a back boiler or a stove in the house. As far as i'm aware the only change to the original heating system was when I bought the house I put in a condenser boiler

Wearb

Its then likely to be plumbed poorly or maybe circulating pump set too high. There are some simple fixes, like combined F&E pipes, or maybe its simple enough to correct the plumbing. But seeing as you have already had a plumber with eyes on the system, I would be inclined to go with his suggestion.

RJF

Should be an easy fix for a plumber who knows what he is doing.

First things- is the heating vent going to the small tank?
Is the cylinder vent going to the large tank?
Is the small tank located on top of the large tank?
Do they have separate overflows to outside?
Is the circ pump on 3, 2, or 1.

Irish Steve

To add to the list, if it's the small tank that's heating, has the system been fitted with Thermostatic valves? If yes, are they closed, so limiting the flow through the system?

Are there radiators on the system that have been turned off? If the flow and return to the roof tank are not on the same side of the pump, and the valves are closed, it's possible for the pump to be circulating through the tank.

Another possible is that the radiators may be partially blocked, so the pump is providing enough pressure to circulate to the roof tank level via the air release pipe.

I'd be reluctant to convert the system to a closed system without being sure that there's not another underlying issue that is causing the problem.

Evenidonhnaill

Would getting the system flushed then to make sure no blockages be a better first approach?

RJF

Evenidonhnaill wrote: »

Would getting the system flushed then to make sure no blockages be a better first approach?

Not unless you want to spend up to 600 euro to do something that may or may not help.

If you answer the questions asked previously we may be able to point you in the right direction.
We still don't know if it's the small or large tank that's overheating?
What setting on circulation pump?
etc. ......?

Evenidonhnaill

RJF wrote: »

Not unless you want to spend up to 600 euro to do something that may or may not help.

If you answer the questions asked previously we may be able to point you in the right direction.
We still don't know if it's the small or large tank that's overheating?
What setting on circulation pump?
etc. ......?

Its the small tank not the large one and the circulation setting on pump was reduced by plumber when he was here but it didnt stop the problem. just doubled checked and he set it at 1.

all radiators are on but one or two upstairs only half heat bot sure if this is enough to cause the hot water to pitch into tank in attic though.

As for the two tanks having different overflows i have no idea and not sure what i would be looking for if i'm honest.

As for the cost for flushing the radiators i doubt it will be 600 as my mum just got it done for a lot cheaper and she has nearly triple the amount of radiators I have and two weren't working but now are heating perfectly. (dont know if its cheaper if you have less)

Dtp1979

Evenidonhnaill wrote: »

Its the small tank not the large one and the circulation setting on pump was reduced by plumber when he was here but it didnt stop the problem. just doubled checked and he set it at 1.

all radiators are on but one or two upstairs only half heat bot sure if this is enough to cause the hot water to pitch into tank in attic though.

As for the two tanks having different overflows i have no idea and not sure what i would be looking for if i'm honest.

As for the cost for flushing the radiators i doubt it will be 600 as my mum just got it done for a lot cheaper and she has nearly triple the amount of radiators I have and two weren't working but now are heating perfectly. (dont know if its cheaper if you have less)

Your issue prob not sludge so shouldn't need powerflushing. As a guide, powerflushing costs approx 450-500. Once you've more than say 15 rads the price will go up.
Aside from that, can you take a pic of your Hotpress pipework showing everything in one pic if possible.

RJF

Evenidonhnaill wrote: »

There isn't a back boiler or a stove in the house. As far as i'm aware the only change to the original heating system was when I bought the house I put in a condenser boiler

What is the make and model of the boiler?
Is the circulation pump on the flow or return?

Evenidonhnaill

Dtp1979 wrote: »

Your issue prob not sludge so shouldn't need powerflushing. As a guide, powerflushing costs approx 450-500. Once you've more than say 15 rads the price will go up.
Aside from that, can you take a pic of your Hotpress pipework showing everything in one pic if possible.

Is there a specific way to upload photos on here?

RJF

You can't upload photos until you have made 50 posts.

Dtp1979

Evenidonhnaill wrote: »

Is there a specific way to upload photos on here?

Just go into after hours and post 50 full stops