Gravity fed boiler warms radiators first.

[Nijinski001]

It's winter again and it's brought home a problem we've had for the last 5 years since we moved to this house.

We have a gravity fed hot water system with the hot water tank in the airibg cupboard and central heating pump below the boiler.

The problem is when we get up ona cold morning the heating is on and warm but because the central heating pump is on the go the water in the tank is not hot enough for a shower.

Is this a symptom of the system or is there something wrong?
Is there a way I can get the tank water hotter for first thing in the morning?

Cheers

 

[chrishutt]

Switch hot water on earlier than central heating?

 

[Bylough]

Excuse me-Mr-(never assume anything!), but this sounds like a 'no seperate hot water system' to me- but I don't know the answer so I'll duck out again!!

 

[Nijinski001]

Your right Bylough. No separate hot water.........
Anyone any ideas?

 

[slippyr4]

The CH pump will, if you like, suck the hot water through the rads. There will be not very much flow through the DHW side while the pump runs. That's just how it is with gravity HW.

Your solutions are, a) as chris said or b) get it converted to a fully pumped and fully controlled system/

I know which i'd choose.

 

[chrishutt]

No separate hot water.........

What's that supposed to mean?

 

[Nijinski001]

Both work from the same timer and control panel and no way to separate the flow of water or restrict one or the other

 

[Gasman1015]

So you are saying that in the summer you have to have the radiators on as well as the hot water.

Most gravity systems will allow the boiler to heat water only and the timer is mainly for the pump on radiators.

Therefore what chris is trying to tell you is correct.

 

[chrishutt]

I think he's saying that the timer allows HW only or HW and CH, but only allows one set of timings, which is normal on old timers. So one answer would be a new timer which allows different timings.

Of course converting to fully pumped would be altogether better, but much more expensive.

Still no explanation of "no separate hot water" anyone?

 

[Gasman1015]

Try turning pump speed to low.

 

[Nijinski001]

Okay let me explain as best as a non plumber can.

Timer controls the ignition to the boiler AND the CH pump.
To have hot water in the summer I have to keep the boiler switched on and turn the thermo down for the CH. Because it is a gravity system the upstairs rads get hot so I have to turn them off.
In the winter the heating is turned up to a reasonable level but this seems to take the majority of the water from the tank and doesn't replenish quick enough to enable hot water for shower etc.

Ther is no method of separating the flow of hot water into the tank and central heating system.

 

[ollski]

Okay let me explain as best as a non plumber can.

Timer controls the ignition to the boiler AND the CH pump.
To have hot water in the summer I have to keep the boiler switched on and turn the thermo down for the CH. Because it is a gravity system the upstairs rads get hot so I have to turn them off.
In the winter the heating is turned up to a reasonable level but this seems to take the majority of the water from the tank and doesn't replenish quick enough to enable hot water for shower etc.

Ther is no method of separating the flow of hot water into the tank and central heating system.

I don't follow, a gravity hot water / pumped ch will probably have a switch for either hw only or both. When on hw only the antigravity valve should prevent any heat being lost to the rad circuit, the pump should only come on when switched to heating and hot water. Sounds like your anti gravityvalve is passing.

 

[chrishutt]

There is no method of separating the flow of hot water into the tank and central heating system.

But a new timer with some alterations to the wiring would allow the pump and boiler to be timed separately, so the boiler could start heating DHW only at say 6 am and then at say 7.30 am the pump would come on, heating up the rads.

 

[Nijinski001]

Oli
Where is this switch likley to be?
I don't recal ever seeing one.

Thanks for the new switch suggestions.

 

[Registered Gas Man]

Gravity! Time for an upgrade maybe?