£3,700 spent on our new (HEAT ONLY) boiler and a tad dissapointed because no hot water after 2 baths

coffeehound

Le_Kirk said:

What temperature is your thermostat (the one strapped on the hot water cylinder) set at?  It needs to be over 60.

Also, check what the boiler flow temperature is set to.  It needs to be higher than the thermostat setting in order to achieve the set temperature.

TELLIT01

I haven't seen any mention of an immersion heater in the hot water tank.  It's possible that it has failed and the water is only being heated by the boiler.  If that is the case I'm not surprised there is limited hot water by the time the 3rd person needs it.

Jeepers_Creepers

Good point, TELLIT - have the immersion running throughout the showering periods, but only then. That'll help.

FreeBear

Jeepers_Creepers said: 2) Raise the cylinder temp to - ooh - 75oC or perhaps more.

Setting the water temperature too high, especially in a hard water area, will see a massive build up of scale inside the tank. Whilst I see your point that the hotter water won't be used as quickly, 60°C is plenty hot enough. If there is a concern about Legionella, maintaining a temperature of over 55°C for a couple of hours will kill off the bacteria.

Fitting a larger tank is an option, but the OP will need to check that the joists under it can take the extra weight.

getmore4less

Pretty much agree with everyone.
this would be my list 
1. Boiler temp up so the stored water heats up quicker  (will make the radiators hotter as well which may be a problem)
2. Tank stat higher so the water is hotter use less needs  mixing same issues with being too hot.
3. Timer for water set to fully charge the tank(30mins-1hr) and stay on till peak use is over.
4. lower water use and try to spread the timings a bit more
5. last resort, immersion

Might also be worth turning off the space heating during water use time to make sure full flow is going to heat the tank.
There may be an issue that the return water is too hot and the boiler cycles

I have a timer/temp on our water tank so can have our tank super hot for bath time and shower temp when no baths are going to happen  and just hot the rest of the time.

lemondrops69

FreeBear said:

Jeepers_Creepers said: 2) Raise the cylinder temp to - ooh - 75oC or perhaps more.

Setting the water temperature too high, especially in a hard water area, will see a massive build up of scale inside the tank. Whilst I see your point that the hotter water won't be used as quickly, 60°C is plenty hot enough. If there is a concern about Legionella, maintaining a temperature of over 55°C for a couple of hours will kill off the bacteria.

Fitting a larger tank is an option, but the OP will need to check that the joists under it can take the extra weight.

And if you set it above 60C/65C and you have a shower pump it can cause them to fail and will definitely void most manufacturers warranties  

Jeepers_Creepers

lemondrops69 said:

FreeBear said:

Jeepers_Creepers said: 2) Raise the cylinder temp to - ooh - 75oC or perhaps more.

Setting the water temperature too high, especially in a hard water area, will see a massive build up of scale inside the tank. Whilst I see your point that the hotter water won't be used as quickly, 60°C is plenty hot enough. If there is a concern about Legionella, maintaining a temperature of over 55°C for a couple of hours will kill off the bacteria.

Fitting a larger tank is an option, but the OP will need to check that the joists under it can take the extra weight.

And if you set it above 60C/65C and you have a shower pump it can cause them to fail and will definitely void most manufacturers warranties  

Neither the scale issue nor the possible damage to a pump occurred to me. Good points.

Ganga

Is it possible to have a combi type boiler and a hot water tank? that way they would have the tank of hot water to start the shower marathon but with access to hot /warm  water from the boiler .

nofoollikeold

1. As others have said, bigger tank.
2. Another suggestion - replace existing tank with a fast recovery one.  

Ectophile

Here's my thoughts to add to the collection...

• Only use an immersion heater as a last resort.  It will cost at least 4 times as much to run as the gas boiler.

• Set the boiler timer to come on at least 1/2 hour before the first bath, so the tank is nice and hot.  Keep the boiler timer on all the time that you have baths, so while one person is having a bath, the water is reheating ready for the next one.
• Set the thermostat to 60 to 65 degrees, for safety against Legionella.  Above that, the boiler becomes less efficient, as the condensing feature doesn't really work.