Direct Unvented Tribune Boiler

Saddler1975

Hi, we have recently moved into a new apartment which only has an electric supply.

We have a direct unvented Tribune 150l cylinder and are having trouble getting enough hot water for one shower. We have the timer on for 61 mins during the morning as stated in the hand book and that should heat the whole tank which should stay hot/warm for near enough the whole day (if not used), but when we get home it's a fight to see who gets the hot water.

We only have a bog standard built-in shower that runs off the hot water so surely a 150l cylinder should be plentiful for us both to have a shower?

molerat

Does it have 2 elements ? If so which one are you heating the water with - upper or lower ?

Saddler1975

molerat wrote: »

Does it have 2 elements ? If so which one are you heating the water with - upper or lower ?

Im not 100% sure as I asked a plumber today and he said it's only got one but I think it's got two as I have two thermostats, one for Boost (top) and one for timer (bottom) which is the one we use for an hr in the morning.

Saddler1975

Just had a read of the manual and I believe it has 2x3k/w immersion heaters.

molerat

I assume you are on an E7 tariff as you heat the water in the morning so maybe give it another half hour and see how it goes. I think 61 minutes is not really enough http://www.withouthotair.com/c7/page_50.shtml

macman

Assuming you are on E7 then you are using it wrongly. The boost is only intended as a top up, and boosting it outside of the E7 hours costs you about 350% more. Put the main element on for maybe 2 hours overnight (on the cheap rate hours-say 4 until 6am)) and you should have a full hot tank at a much lower cost. If the tank is properly lagged, that will stay hot all day

Saddler1975

macman wrote: »

Assuming you are on E7 then you are using it wrongly. The boost is only intended as a top up, and boosting it outside of the E7 hours costs you about 350% more. Put the main element on for maybe 2 hours overnight (on the cheap rate hours-say 4 until 6am)) and you should have a full hot tank at a much lower cost. If the tank is properly lagged, that will stay hot all day

As suggested by yourself and Molerat it appears that 61 mins would not be enough so as from this morning I have set the timer from 5am to 7.30am. We do not have a E7 tariff we have an alday tariff of 10.4p p/kw which I believe us pretty good so using the boost (which we do not use anyway) should not cost anymore than using the timer.

P.s this is one of those silly questions which will have an obvious answer but my brain is not working this morning, If the thermostat is set at 65 degrees what difference does it make if it's in for 60mins or 150mins as the thermostat will just kick in once it's reached that temp? I am preparing for a whoosh or something more deservedly lol

matelodave

You are correct that once the tank has got up to 65 degrees then the thermostat will switch it on & off to maintain 65 degrees but if the heater isn't on long enough to heat the tank up to 65 then the thermostat won't be able to do it's job.


It takes 1 kCal to raise 1kg (~1 litre) of water by 1 degree C.

1000 kCal = 1.163 KWh

For a 150 litre tank and assuming that the water is about 15 degrees and is being heated to 65 degrees (temperature rise of 50 degrees)

150 x (65-15) = 150 x 50 = 7500 kCal = 8.722kwh so a 3kw immersion will take about 2.9 hours to heat the tank to 65 degrees, longer if the incoming water is colder.


Perhaps you should try to use less hot water. Take shorter showers or fit a flow restrictor. Some showers can flow at 15 lpm so standing in there for 10 minutes will use 150litres of water. Restricting your shower time to five minutes will halve that to 75 litres and fitting a flow restrictor or economy shower head could halve it again to 35 litres. Saving you both energy and water and making sure there's enough hot water for both of you

Saddler1975

matelodave wrote: »

You are correct that once the tank has got up to 65 degrees then the thermostat will switch it on & off to maintain 65 degrees but if the heater isn't on long enough to heat the tank up to 65 then the thermostat won't be able to do it's job.


It takes 1 kCal to raise 1kg (~1 litre) of water by 1 degree C.

1000 kCal = 1.163 KWh

For a 150 litre tank and assuming that the water is about 15 degrees and is being heated to 65 degrees (temperature rise of 50 degrees)

150 x (65-15) = 150 x 50 = 7500 kCal = 8.722kwh so a 3kw immersion will take about 2.9 hours to heat the tank to 65 degrees, longer if the incoming water is colder.


Perhaps you should try to use less hot water. Take shorter showers or fit a flow restrictor. Some showers can flow at 15 lpm so standing in there for 10 minutes will use 150litres of water. Restricting your shower time to five minutes will halve that to 75 litres and fitting a flow restrictor or economy shower head could halve it again to 35 litres. Saving you both energy and water and making sure there's enough hot water for both of you

Are the flow restrictors universal? I have a built in shower head that is connected to the hot water pipe behind the wall tiles (obviously).

P.s just ordered a water flow restrictor (4lpm) off eBay, thank you

matelodave

You might find that 4lpm is a bit low for a shower, mine is about 7lpm and works well. It fits between the shower head and the pipe that it screws onto.

Check with your water co, they quite often give them away. I got one for the shower and a couple for the taps on the bathroom & kitchen sinks. The sink ones help as my wife is incapable of turning the tap on halfway, full bore or off so it reduces waste when she is rinsing stuff.

Saddler1975

matelodave wrote: »

You might find that 4lpm is a bit low for a shower, mine is about 7lpm and works well. It fits between the shower head and the pipe that it screws onto.

Check with your water co, they quite often give them away. I got one for the shower and a couple for the taps on the bathroom & kitchen sinks. The sink ones help as my wife is incapable of turning the tap on halfway, full bore or off so it reduces waste when she is rinsing stuff.

Thank you I will see how we get in with it and if needs must get a different one.

The wife has just had a 15min shower and just started to go cold as she was finishing so appears our shower head does release water at about 15lpm.