navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Biomass boiler DHW plumbing pump question  (Read 1275 times)
Burnt toast
Newbie
*
Offline Offline

Posts: 21


« on: August 17, 2017, 01:13:42 AM »

Hi
We installed our log gasification boiler a few years ago but kept on using our electric shower. We want to get rid of this now and use the hot water tank.

Both the boiler and the hot water storage tank are in the basement. The accumulator tanks are on the ground floor, but these are not to be used for DHW supply.

So I need to improve the water pressure for the shower as the shower head itself is about 3m above the top of the hot water tank. I had planned to install a twin impeller pump under the bath but these need 1m of head minimum for their supply. That's no problem for the cold feed comes from the header tank in the loft. However, I reckon I need another pump in the basement to get the hot water to the twin impeller pump at a reasonable pressure.

Can someone please make a recommendation for that pump, and also comment if I really even need the twin impeller pump.

Many thanks
Logged
Iain
Hero Member
*****
Offline Offline

Posts: 1541


« Reply #1 on: August 17, 2017, 07:44:21 AM »

Hi

Quote
.So I need to improve the water pressure for the shower as the shower head itself is about 3m above the top of the hot water tank. I had planned to install a twin impeller pump under the bath but these need 1m of head minimum for their supply. That's no problem for the cold feed comes from the header tank in the loft. However, I reckon I need another pump in the basement to get the hot water to the twin impeller pump at a reasonable pressure.  

Where is the header tank for the hot water cylinder?
Normally it is the same as your cold one, other wise you wont be able to use any hot water above the basement level.
If it is the same tank, you will have a balanced supply and a twin impeller pump will be fine.
Iain
« Last Edit: August 17, 2017, 07:46:54 AM by Iain » Logged

1.98kWp PV  (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
9000ltr rainwater storage   Plymouth
http://www.bdpv.com/fiche_utilisateur_en.php?util=iain
http://www.sunnyportal.com/Templates/PublicPageOverview.aspx?plant=cba8d47f-bf09-4533-a105-4303b353f20f&splang=en-US
Burnt toast
Newbie
*
Offline Offline

Posts: 21


« Reply #2 on: August 17, 2017, 01:40:11 PM »

Hi

Quote
.So I need to improve the water pressure for the shower as the shower head itself is about 3m above the top of the hot water tank. I had planned to install a twin impeller pump under the bath but these need 1m of head minimum for their supply. That's no problem for the cold feed comes from the header tank in the loft. However, I reckon I need another pump in the basement to get the hot water to the twin impeller pump at a reasonable pressure.  

Where is the header tank for the hot water cylinder?
Normally it is the same as your cold one, other wise you wont be able to use any hot water above the basement level.
If it is the same tank, you will have a balanced supply and a twin impeller pump will be fine.
Iain


Hi Iain
We only have the one header tank. We used to get decent pressure out the bath taps, but since we fitted the thermostatic valve we get nothing out the shower head, which is about 1.5m above the taps, but still about 1m beneath the bottom of the header tank.
Logged
Iain
Hero Member
*****
Offline Offline

Posts: 1541


« Reply #3 on: August 17, 2017, 04:39:18 PM »

Hi
Sounds like the same header tank does both the cold and the hot.
So the head for both the hot and cold is the same. (it is not the distance above the HW tank that is an issue, as the HW cylinder is fed from the header tank above, same as the cold)
Do you still get a good flow from both bath taps? or has that changed?
If you do the hot flow/pressure is ok.
Is the problem just the shower?
I assume the shower mixer comes from the same pipework as the bath?
If the above is correct a twin impeller pump under the bath should sort it.

Iain
« Last Edit: August 17, 2017, 04:42:21 PM by Iain » Logged

1.98kWp PV  (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
9000ltr rainwater storage   Plymouth
http://www.bdpv.com/fiche_utilisateur_en.php?util=iain
http://www.sunnyportal.com/Templates/PublicPageOverview.aspx?plant=cba8d47f-bf09-4533-a105-4303b353f20f&splang=en-US
Burnt toast
Newbie
*
Offline Offline

Posts: 21


« Reply #4 on: August 17, 2017, 10:23:11 PM »

Hi
We had regular taps on the bath. They filled the bath quickly. Then we swapped them out for a thermostatically controlled mixer tap with shower head attachment. Now we get a very slow dribble. Hot and cold, but hot is worse
Logged
Iain
Hero Member
*****
Offline Offline

Posts: 1541


« Reply #5 on: August 18, 2017, 06:22:30 AM »

Hi
So it is just the thermostatic mixer that has caused all the problems?
So in the past there was no issue with flow rates.
Most thermostatic mixer valves struggle with low head systems. What is the manufacturers minimum head required for your mixer valve?
Aqualesa used to do mixers specifically for low head systems but needed 22mm pipes. Not sure if they still do.
So a twin impeller pump should solve your issues, feeding both the bath and shower via the new mixer.
Iain
Logged

1.98kWp PV  (11 x Sharp 180 and SB 2.5)
20 x 65mm Thermal and 180ltr unvented
9000ltr rainwater storage   Plymouth
http://www.bdpv.com/fiche_utilisateur_en.php?util=iain
http://www.sunnyportal.com/Templates/PublicPageOverview.aspx?plant=cba8d47f-bf09-4533-a105-4303b353f20f&splang=en-US
brackwell
Hero Member
*****
Offline Offline

Posts: 2496


« Reply #6 on: August 18, 2017, 07:33:48 AM »

When you swopped could you now have air trapped. Thats what happened to me.

Ken
Logged
Burnt toast
Newbie
*
Offline Offline

Posts: 21


« Reply #7 on: August 19, 2017, 06:56:42 AM »

Thanks for the input guys, I will give that a go.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!