How much hot water should I expect?

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How much hot water should I expect?

Post  animal on Wed Nov 17, 2010 8:41 am

We have recently had a 'stat replaced on our Pulsacoil 2000 which we were told was the reason we weren't getting proper hot water, just warm at best.

We do now get sufficiently hot water but we just dont seem to get enough of it.

The bottom element runs off a timer that I have set to operate between 22.00 and 06.00 - more or less, off peak.

First thing in the morning one of us can have a decent shower, lasting between 5-10 minutes. But that's it.

Try to have another shower or even run a hot tap and the water is mildly warm at best, immediately after the first shower.

Surely we should expect a bit better than that? I understand how the system works, so I'm baffled how a tank heated to approx. 70 degrees over night can be cooled by the heat exchanger so dramatically after just one shower?

Based on this, there is simply no way we could ever hope to run a bath. There's never any hot water in evening when we get home to wash-up or even have another shower after work and as such we are having to boost the tank on-peak at considerable extra cost.

Am I being unrealistic in my expectations of more than one hot shower a day or is something wrong? I understand that a shower in the evening would be a bit cooler than first thing as temperature will be lost over the course of the day. But the fact that one shower in the morning is wiping out the heat store entirely in under 10 minutes just doesnt seem right to me.

We are in rented property, so at the moment we are having to 'make do' with cut-price contractors instructed by the letting agency who don't appear to have clue about the Pulsacoil system. The new 'stat isn't a proper replacement and is a standard unit with a black end and only goes up to 70 degrees as opposed to the turquoise one orginally fitted which I believe get a bit hotter?

Any advice or input is greatly received. Thank you.

animal

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Re: How much hot water should I expect?

Post  mike on Thu Nov 18, 2010 12:25 pm

The stat need to heat to 72c
Also flow or limiters are recommended in the book
What size unit is it?
Could it be sludged up?
So you have not got the amount of water you should have in the unit.
Is the unit full?

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Re: How much hot water should I expect?

Post  animal on Fri Nov 19, 2010 9:37 am

mike wrote:The stat need to heat to 72c
Also flow or limiters are recommended in the book
What size unit is it?
Could it be sludged up?
So you have not got the amount of water you should have in the unit.
Is the unit full?

Hi Mike,

Thanks for your response. I will confirm the unit size when get home later but i think it's 170l.

I have set the stat to it's max level, which is indicated as 70c - bit it's clearly not a like-for-like replacement stat and I wanted to be sure it hadn't been bodged? It appears to be a generic rod stat, and is different in appearance to the original item. An original stat is still fitted to the top element. I've read somewhere on here that these heat to around 90c - is the generic stat stopping the heat store from getting hot enough, hence why it's not lasting long? Would it be worth swapping the stats around?

The water level in the top tank was low, but I topped this up to the molded line, so I assume the water level in the heat store is ok. I did this before the electrician was called out to see if it was the cause of our problem but it hasn't made any difference.

We had the same problem again this morning. My wife had a shower and the water temperature was fine. Almost too hot to stand under if the hot tap was turned all the way up, so more than adequate. But after a single 8-10 minute shower, the heat store seemed to be completely depleted. After her shower, all I could get from the taps was luke-warm at best, which surely isn't right? I don't understand how a the large body of water that is in the heat store could drop in temperature so significantly after just a one shower.

Clearly some water is being heated and everything works for approx. 10 mins of continuous use but then it drops off and all we get in luke-warm water unless the system in boosted. When we first moved it, we definitely had more hot water for longer i.e. at least two showers, one in the morning and one in the evening plus washing up.

How would I be able to tell if the system was sludged-up?
And what do you mean by flow or limiters being recommended in the book?

Incidently, the status LED is not indicating an issues.
Water temperature is stable when it is running hot, suggesting the thermistors are all ok.
We do live a very hard water area. However, the heat exchanger is clearly working as for the 10 mins we get hot water, it is very hot. It just doesnt last.

Thanks again for your time. I appreciate you taking the time to help out.

animal

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Re: How much hot water should I expect?

Post  mike on Fri Nov 19, 2010 10:46 am

Answers
Wrong stat fitted
Swop the stats round.
170 litres should give you enough.
As an experiment, you could try over the week end running water into 2 or more buckets bucket say 5 to 10 litres each.
2 people required keep filling and emptying and count till the water runs out. Then you will know how much available.
To find out if sludged up or blocked you will have to drain some water out of the unit and see what colour and if the top tank level drops.
If it don't drop then cold feed is blocked.
In the book it is advised that flow limiters are used to level the flow to all the taps in the house.
Down load a free book from Gledhill's web site
You will not see any lights etc ref to fault as these problems will not show up.
Also lets say you have 170 litres of hot water storage, but there is 10 litres of sludge see where I am coming from.
Or the unit is only 3/4 full then the heat store will be less


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Also check the pump

Post  sunny.sahdev on Mon Sep 23, 2013 4:47 am

I agree with everything Mike has said. I would also check the pump is spinning at 60v and increases routation as the volts increase.

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