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

FrankFalcon

We have recently moved into a new house.  We knew before we moved in that the Boiler had been condemned and were given £2,000 by the vendor towards a new one.  So, we have no complaints up to here.  So, as soon as we were in the house we contacted a local Gas Safe engineer.  He called round and we told him that we knew it would be a sizeable outlay so we wanted to 'Change' our system.  The conversation went as follows:
Me: We are a family of 6 and all need the shower/bath at relatively similar times of the morning.  Whist we have the chance we want to install a system that will allow us to do this because in our other house it wasn't possible because the Combi couldn't deal with 2 - 3 showers at once. 
Him: You are in luck because your current system has a hot water tank in place.  You only need a new heat only boiler.
...So, he quoted us £3,700 to replace (and remove it to another part of the house) the condemned boiler for a brand new Worcester heat only boiler with a 10 year warranty.  No complaints up to now...

I must add in here that I got 3 prices off Gas Safe engineers and they were all similarly priced.  

The 2 guys were literally with us 2 days (there was a lot of old pipes taken away at the end of the job) and they have done a great job of fitting this new Worcester boiler.

So, the system is up and running but we find that after 1 person has had a bath the water is not very hot for the 2nd and the third person has cold Water.  We thought it was a fault so we called the engineer out and he told us this:
Him: I didn't say you could have lots of showers one after the other.  I said you could run 2 -3 showers at the same time but after that you would need to give it time for the water to heat up again.  
So, it appears we have misunderstood him.  We have no reason to think he'd lie to us.  He went on to tell us...
Him: Your current tank is 210L but of that only 180L will be hot Water (Don't understand why?).  You could upgrade the tank size or add another one next to it.
Can anybody provide any advice? I don't want to cause any trouble with the man.  His stance is he's done what we asked him, which may be the case.  I know some people will say we should stagger our shower times but that is not a solution to the issue.  Anybody have any thoughts?

daveyjp

Install an electric shower.

Doozergirl

Yes.  The tank isn't big enough for your needs.  

Thankfully you didn't just buy the too-smallone you have. 

Your engineer has done what he said.  

If you want a bigger tank, go for it.  It would be a good idea to do some maths on how much water you're wanting to use in one go, so you size the tank correctly.   

Also make sure that the boiler is timed to heat the water fully before everyone heads for the hot water, and that it's also set to refresh it immediately.  

Le_Kirk

What temperature is your thermostat (the one strapped on the hot water cylinder) set at?  It needs to be over 60.  Where on the cylinder is it.  Maybe this is why your chap said only 180 out of 210 would be hot because the thermostat is affixed quite high up the cylinder.  If you place it lower down it will cause the boiler to fire for longer and give you more hot water.  Coupled with the advice from @Doozergirl that should help.

Hasbeen

We have a 1700mm high Cylinder. Believe capacity is circa 280 litres.

Our main bath is 180 Litres.
"Standard/average bath has a capacity of 180 litres to the overflow. Home Test: 1700 x 700mm bath with capacity of approximately 175 litres to overflow. Used:- 70 litres of hot and 30 litres of cold and produced a bathing temperature of 40'C."

Some info here on average usage:

Hot Water Cylinder Sizes

Determining hot water cylinder sizes is one of the most critical parts in designing efficient hot water systems to ensure they meet the demand.  

Over specifying your hot water cylinders will use more energy to heat hot water which simply isn’t required. However, designing cylinders to be too small will inevitably result in a lack of available hot water.

Whilst every project will have its own specific needs, the starting point is to understand what the potential hot water demand is likely to be over the course of a day and at peak periods.

So as a rule of thumb you will use:

• 70-80 litres of hot water to run a bath
• 45 litres of hot water for a 5 minute shower
• 50-100 litres of hot water for a full load in the washing machine12-20 litres of hot water per cycle in the dishwasher
• 0.2 litres of hot water per second when you run the kitchen taps
• 0.15 litres of hot water per second when you run the sink taps

However calculating the optimum size for hot water cylinders isn’t a case of multiplying the above by the number of people in the property.

The main consideration is understanding the peak demands and ensuring you have the right combination of cylinder capacity and re-heat times.

Choices are get a bigger tank, Use more showers, Investigate getting one of these?
 RM Cylinders 600Ltr Indirect Unvented Hot Water Storage Cylinder | Unvented Hot Water Cylinder | Screwfix.com

Jeepers_Creepers

Pretty much as said above. And the guy has done nothing wrong.

Obvious steps:

1) Have the hot cylinder set to be fully charged before the morning showers - give it a good hour to be sure - and then timed to remain on throughout and for a half-hour after the last shower. I suspect you already do this?

2) Raise the cylinder temp to - ooh - 75oC or perhaps more. That will use less hot water for the showers, as the shower (thermostatic, obviously) will automatically blend in more cold. Obviously, 75oC is BLUDY HOT, so you need to be aware of the risks of scalding, and perhaps fit thermo taps as well, to any sink/basin that a dependent may use. See what other folk say about this move, including plumbers...

3) Limit the water use from each shower if you know there will be follow-ups. Either folk behave more considerably and turn the flow down, or else you tweak shut the isolating valves to each to force the issue.

If that fails, fit a larger hot cylinder.

theoretica

Your tank size full of hot water is the most you have to work with.  Options you have include using less water each - shorter showers, shallow baths, water reducing shower heads, turn the shower off while you soap up.  It is possible to get clean using far less water than most people use.  You could as suggested try increasing the temperature of water in the tank so you mix more cold in which will make the tank you have go a little further.  

Spank

In the meantime, some of you can shower the night before.

Apodemus

I'd leave it as it is - nothing like limited hot water to encourage the family to be up early! 

chrisw

Whoever has the bath is using more than their fair share.

Ibrahim5

We have 4 bathrooms with 3 showers and 2 baths. We have a 210 litre tank. We have no problems but we don't use everything at once. It's hard to say what is reasonable. There is no right answer. You can't expect limitless flows and volumes.