2 pump system

[sln8458]

Hi guys, please be gentle I'm new here.

My guvnor, she who wears the trousers has been complaining more & more recenltly about the lack of HOT water.

The system at present is a standard gravity HW & pumped CH.
Boiler is freestanding, & as we live in a bungalow, the hot water tank is not very high. (the bottom of the tank is approx level with the top of the boiler).

While there was only the 2 of us the hot water system could cope, but as the family has grown both in size (now 5 of us) and age the hot water system has struggled.

The heating system works fine (did when I left this morning anyway) When we only need hot water the boiler cycles on & off via the boiler thermostat, but the water in the tank takes hours to heat up

I have been considering installing a second pump in the hot water feed to the tank to improve the circulation, my assumption as to the real cause of this problem, so to my question(s).
Can I do this ? is it allowed?
If so - how do I do it?
Where is the best location for the pump?
How do I wire it up?

Any help would be much appreciated.
SteveN

 

[chrishutt]

You should consider an overall upgrade of the system, including pumped circulation to hot water cylinder.

A second pump on the existing gravity return circulation pipe is possible but you ought really to have a motorised valve and cylinder stat to properly control HW temps and boiler cycling.

Better to alter the pipework so you run the flow pipe from the existing pump through a 3 port mid position valve (or 2 x 2 port valves), plus a cylinder stat and room stat if you don't have these. Materials for this might cost £50.

Even better might be to replace the cylinder with a modern (larger?) one with better insulation and a faster recovery coil - £100+ depending on size.

 

[sln8458]

chrishutt

Thanx for your comments.

You should consider an overall upgrade of the system, including pumped circulation to hot water cylinder

By this do you mean DHW or the complete central heating system

A second pump on the existing gravity return circulation pipe is possible but you ought really to have a motorised valve and cylinder stat to properly control HW temps and boiler cycling.

I can go with this, no stat on the tank at present (would be redundant at the mo' ) but why the MOV

Better to alter the pipework so you run the flow pipe from the existing pump through a 3 port mid position valve (or 2 x 2 port valves), plus a cylinder stat and room stat if you don't have these. Materials for this might cost £50.

I would prefer to keep the two systems as independant as possible, hence why I have not mentioned that route.
Room stat - yes.
Stat valves on all rad's.
No stat on tank.

Even better might be to replace the cylinder with a modern (larger?) one with better insulation and a faster recovery coil - £100+ depending on size

.

This is an option I will consider, tho' I am restricted on space.

Just remembered that I raised the tank some years back, when the comments started so I know that this is not an option.
The tank & boiler are back to back on the same wall.

Any other comments
SteveN

 

[chrishutt]

I can't really get involved in trying to explain all the ins and outs of central heating with you (unless you'd like to pay me my normal hourly rates ) but I would just add that with pumped circulation to cylinder it might not need to be raised above level of boiler.

If you want to spend a few days studying the background to my comments you will find a wealth of information on this forum (do a search) and elsewhere on the web.

 

[ChrisR]

At the moment your boiler is on all the time your programmer has the HW on. If you pumped the HW side the pump would be on all the time so you'd need to control it, and the CH, somehow; hence MV's.

Whether it would be easier to add an extra pump or use just one in a normal (say ) S plan configuration would depend largely on access, and what you have already. If access is OK, expect to pay a couple of hundred for someone to bring it up to date. Parts would be more than £50 I expect.

Presumably you've got the boiler temperature turned up - this would reduce HW reheat time and make it hotter.

 

[sln8458]

ChrisR

Presumably you've got the boiler temperature turned up - this would reduce HW reheat time and make it hotter.

Boiler is set to 6 (max setting) when we need hot water, normally 2 - 3 on Heating.

Chrishutt

The reason I asked about the MOV is, if I have a second pump controlled by a new stat on the tank surely this would stop almost all of the gravity circulation when de-activated. (had you lived a little closer then I would be happy for you to pay for your time )

but I would just add that with pumped circulation to cylinder it might not need to be raised above level of boiler.

one of my reasons for thinking about the second pump


To recap so far:
A second pump is OK, with a new stat on the tank & possibly a new tank,
Pump located in the return leg.
The existing tank has insulation bonded to the outside, so some of this would need to be removed to locate any new tank stat.


Best location for this The lower the stat the more hot water, but the water at the top of the tank would be hotter than the setting on the stat, yes

Found the answer for this one

Stats are usually placed 1/4 to 1/3 way up cylinder

How would this be wired? including an MOV

SteveN

 

[chrishutt]

You're asking too many questions! And they've all been answered before, so do a bit of searching (if you don't know how, just ask).

Just one answer - the proposed pump will not stop gravity circulation to cylinder when CH is running, so overheating may occur (depending on boiler stat setting). However the cylinder stat will at least stop the boiler running to keep itself warm (cycling) when stat is satisfied.

If you're planning to do this work yourself, you should at least consider getting a heating engineer to look at the existing system and draw up a plan for modifications - unless you're prepared to do an awful lot of homework (and I'm not answering any more your questions!).

 

[sln8458]

Chrishutt

You're asking too many questions! And they've all been answered before, so do a bit of searching

(and I'm not answering any more your questions!).

I'm sorry you feel this way, I have always told the apprentices who work with me that the only silly question is the one you DON'T ask. However I will continue to ask and anyone may answer or not as the case may be

If you're planning to do this work yourself, you should at least consider getting a heating engineer to look at the existing system and draw up a plan for modifications

Yes I am currently considering this, hence my questions
I have contacted a heating engineer, 4 times since mid October, he to is fed-up with me asking for a solution, as I am sure you are aware, good reliable heating engineers are hard to find let alone get prices from.

I am searching this site & found one of YOUR answers to one of my questions, I will continue to search.

SteveN

 

[Mikeyboy]

Do a search on honeywell.On this site you will find all the answers you need.sugest honeywell y plan.

 

[sln8458]

Mikeyboy
Thankyou

SteveN