Thermal store not performing well on day 1

[greenone]

So, the thermal store went in today (320l Navitron). nothing else connected yet so I heated the store with the immersion heater (has its thermostat set to max and is about a third the way up the tank). I waited until the heater clicked off  and then tried the hot tap. Lots of hot water for a few seconds, then rapidly cools down to tepid (the TMV is set wide open, so should be 70C).

I do have a solution, though not a good solution. If I adjust the pressure reducing value until the flow is bordering on pathetic I do get a stream of hot water, but filing the bath might take half an hour at that rate.

all I need out of a fully charged tank is to fill the bath in a reasonable amount of time.

Any ideas on what might be wrong ?

Thanks.

[Justme]

Have the right cylinder tappings been used for the domestic hot water flow?

[KLD]

Can you -- just as an experiment -- turn the TMV fully the other way?
Klaus

[greenone]

hi,
I am as sure as I can be the right tapings are being used. Its a Navitron tank, so the TMV expansion chamber etc arrived fitted to the tank, so only a cold feed in the bottom and a hot out of the TMV required.

I'll screw the TMV  right in and report back on what that does.

Thanks

[brackwell]

From fresh start the bottom third of the tank will still be cold but also when the immersion first switched off it does not mean you had 2/3 hot tank only the water around the thermostat was hot. Perhaps with time the hot water would rise and mix and then the immersion heater would come on again.  This is a lot of water and would take many hours to heat.  I think you may have just been too eager to play with your new toy.

This is not like a normal tank where say40L of hot water at the top of the tank will give you just that. With a thermal store you need nearly a full tank of hot water before it is usable.

Ken

[Countrypaul]

Say you had to heat 200L (approx 2/3 of your tank) and that thecold wate rwa at 20 and the hot at 70, that would require 200*50*4.2*1000J of energy. Witha  3kw heater that becomes 42000000/(3000*3600)hrs so about 4 hours minimum to heat up, but with losses youa re probably looking at longer. How long did you wait for the heater to click off?

Paul

[greenone]

Hi,
thanks, does at the moment look like I am just too eager  . Immersion clicked off after about 2.5 hours. so with the best will in the world with the tank about half charged. I have the immersion on at the moment but am looking to light the rayburn later to really kick it into life. I'll see what happens then.

Thanks.

[carrick]

Come on then, tell us how it's going. I am on the verge of taking the plunge with that store myself, so if the hot water performance is disappointing I'd rather know now.

[Stoozy]

Yep - come on then Hows it performing.  I am also just about to hand over some spondollies.

cheers

Stuart

[gds]

I've got a 20 58mm tube East-West system (40 tube in total) with a 750 litre Akvaterm Solar Plus in Italy. I fitted just the east facing tubes to start with and by 4pm the top of the tank was showing 45ºC, the middle was 38ºC and the bottom was 25ºC. This was hot enough for a shower. After fitting the west facing tubes the following afternoon, it took 2½ days for the whole tank to reach 70ºC.

The pitch of the roof is only 16º so the east facing panel gets the sun until 3pm and the west facing tubes start getting the sun at 10am in the summer. This thermal store has 2 coils for the solar circuit and 2 coils for the domestic hot water circuit. To get max efficency out of the system I fitted a zone loading valve on the solar circuit so the top coil takes priority (heating the top third of the tank) and also fitted two TMVs on the DHW circuit so if the water is hot enough after going through the first DHW coil it will go straight out to the tap/shower etc.

The Solar Plus is very effective. It isn't cheap but £/litre is worth every penny. There is more than enough hot (not tepid) water available for up to 10 people staying at the house at any one time during the summer.

[greenone]

gahhhhhh, sorry for the lack of response. one or 2 other things in life causing stress.

IT WORKS GREAT !

by the time the bath is nearly full the water is down to pleasant warm. and as it is only beiing heated by the waste heat of a rayburn with only the cooker burner lit it takes about 8-10 hours to recover form a bath (we have nice  big bath). for day to day hot water we effectivly have an unlimited supply atm. The gas boiler is now fitted and turned off  it is only there for when everythng else can't cope.

trying to get used to filling the kettle form the hot tap now as that water is also potable.

The plumbers left with a comment of "first time we've seen one of these systems actually work"

[Countrypaul]

Great to hear it working as it should . Now where are those pictures?

Paul

[Stoozy]

Thats great.  hopefuly mine will be as good.  thanks for the feedback.