Solar heat dump

whelzer

My solar system is controlled by a Resol BS (BS/3). I have no heat dump. During the summer my system did overheat so I'm considering getting a heat dump put in. I've to get some plumbing work done before Christmas so might get it done then. Does anyone know if the above controller will allow me to have dump. The manual is unclear. I suspect it may need to be upgraded to the Plus (BS/4). Any pointers much appreciated.

Mike2006

I did something a little bit different.

If m system gets up to temp and needs to dump heat, the system forces the UFH loops in the downstairs and upstairs hallways open until the temp drops in the tank again to a predetermined level.

It was cheaper than a heatdump.

Mike

quentingargan

whelzer wrote: »

My solar system is controlled by a Resol BS (BS/3). I have no heat dump. During the summer my system did overheat so I'm considering getting a heat dump put in. I've to get some plumbing work done before Christmas so might get it done then. Does anyone know if the above controller will allow me to have dump. The manual is unclear. I suspect it may need to be upgraded to the Plus (BS/4). Any pointers much appreciated.

The BS/3 can manage a heat dump. There is a second relay for that purpose. It also may depend on the year you got it because some of the descriptions have changed, but you use what they describe as After Heat. AHo and AHf. If you set the maximum store temperature to, say, 80, set AHo to 75 and AHf to 74, then it will switch on the second relay at 75 and switch it off at 74. If the heat dump should fail to cool the system for any reason, it will still knock everything off at 80.

In choosing those temperatures, I assume you have an anti-scald valve, but you get the idea...

HOWEVER, if you have flatplates, you may be able to use the controller with a different combination of settings to cool the system using the panel and pipework to do the cooling. Come back here and let me know if it is flatplate and I will give you the details (I posted them elsewhere recently on boards). Q

quentingargan

Mike2006 wrote: »

If m system gets up to temp and needs to dump heat, the system forces the UFH loops in the downstairs and upstairs hallways open until the temp drops in the tank again to a predetermined level.

Yes, this works well provided you can ensure that nobody later puts zone controls onto the system that would undermine what you have in place. Q

championc

Mike2006 wrote: »

I did something a little bit different.

If m system gets up to temp and needs to dump heat, the system forces the UFH loops in the downstairs and upstairs hallways open until the temp drops in the tank again to a predetermined level.

It was cheaper than a heatdump.

Mike

Hey Mike

Is this purely dumping heat or are you using it to supplement your general house heating ? I can't decide whether it's worth linking my system to my rads. I have a Kingspan system so don't need a dump really

whelzer

quentingargan wrote: »

The BS/3 can manage a heat dump. There is a second relay for that purpose. It also may depend on the year you got it because some of the descriptions have changed, but you use what they describe as After Heat. AHo and AHf. If you set the maximum store temperature to, say, 80, set AHo to 75 and AHf to 74, then it will switch on the second relay at 75 and switch it off at 74. If the heat dump should fail to cool the system for any reason, it will still knock everything off at 80.

In choosing those temperatures, I assume you have an anti-scald valve, but you get the idea...

HOWEVER, if you have flatplates, you may be able to use the controller with a different combination of settings to cool the system using the panel and pipework to do the cooling. Come back here and let me know if it is flatplate and I will give you the details (I posted them elsewhere recently on boards). Q

Thanks Quentin. Have guy coming around Tuesday to see whats what...

Anthonyk2010

I have a 30-58 mm tube panel heating 200 lt of water and noticed the heat dump was In operation half the amount of time it was last year.
46 hour the dump was in use in 2010 and 22 hours this year.

Could I add another 10 or 15 tubes or would I be pushing my luck.

championc

I assume that the dump option kicked in during the height of the summer and so was possibly at a time when you had no call for any heating anyway. However, i'm surprised you got 22 hours this year. What is the max temp setting of your system before the dump option kicks in ? You could be getting the impression of lots of surplus heat if it was set too low. It's great to have a system which records your data so you can review it later and see what really happened - and when.


C

Anthonyk2010

championc wrote: »

I assume that the dump option kicked in during the height of the summer and so was possibly at a time when you had no call for any heating anyway. However, i'm surprised you got 22 hours this year. What is the max temp setting of your system before the dump option kicks in ? You could be getting the impression of lots of surplus heat if it was set too low. It's great to have a system which records your data so you can review it later and see what really happened - and when.


C

Heat dump kicks in when tank is 68 deg c.

quentingargan

Anthonyk2010 wrote: »

I have a 30-58 mm tube panel heating 200 lt of water and noticed the heat dump was In operation half the amount of time it was last year.
46 hour the dump was in use in 2010 and 22 hours this year.

Could I add another 10 or 15 tubes or would I be pushing my luck.

Yes - if you have a heat dump, you can extend the system as much as you like, and it will, up to a point, extend the operating season safely enough, but the bang for your buck decreases as you will do more dumping of unwanted heat.

There are many reasons why the dump time might decrease - more hot water use coinciding with sunnier days, less sunshing at other times, but also degradation of insulation. However, I wouldn't be too concerned unless there was a clear trend, or you found that water temperatures were unsatisfactory.

Anthonyk2010

quentingargan wrote: »

Yes - if you have a heat dump, you can extend the system as much as you like, and it will, up to a point, extend the operating season safely enough, but the bang for your buck decreases as you will do more dumping of unwanted heat.

There are many reasons why the dump time might decrease - more hot water use coinciding with sunnier days, less sunshing at other times, but also degradation of insulation. However, I wouldn't be too concerned unless there was a clear trend, or you found that water temperatures were unsatisfactory.

I'm not too concerned about the decrease, think it is down to a bad year weather wise.
Why i whould like to add to my panel is to get more out of it in early and late time's of the year.
I think another 10 tubes would do it.