Separate pump in addition to the one included in the condensing boiler?

[hughs]

My main question is whether I need a separate pump in addition to the pump within the condensing boiler.

I am replacing a boiler. The previous boiler was the old open flue type and had two external pumps. The new boiler is a Vaillant EcoTec 630 plus system boiler. The boiler together with the hot water tank are situated in the garage. The boiler also feeds the hot water system to heat up three towel rails (i.e. they are heated whenever the hot water is switched on). There is an independent pump for the showers, which has a separate run to the house and back. The condensate from the boiler will be put into a soakaway adjacent to the garage wall. The pipe run from the beginning of the house and the boiler in the garage is approx 9 metres. The house has 4 bedrooms.

Almost all the engineers suggested that we needed a pump in addition to the pump included in the boiler and the shower pump. My chosen supplier does not believe that a separate pump is required. He states that the boiler pump will be sufficient to pump both the hot water and the central heating system to the house (quite apart from the shower pump which is independent). I am confused. What is the purpose of the additional pump? Is it required for the above system? What part of the system would it pump (i.e. central heating radiators, hot water etc). What difference would I notice if I do not have the additional pump installed?

Urgent advice would be much appreciated. Many thanks.

 

[unguided1]

Hi Hughs
I'm a little confused here can you supply a pic because as I am reading this, is your second pump feeding the showers placed, next to your Hot water cylinder and feeding into it either somewhere near the top of the cylinder or into the cold feed if so as you have stated then this is a secondary return for the hot water system. or are you saying that you have three pumps in total. 2 on the heating circuit and another for the showers. If you have 2 pumps on the heating circuit how many zone valves do you have? Your house doesnt sound that big.

 

[hughs]

Hi Hughs
I'm a little confused here can you supply a pic because as I am reading this, is your second pump feeding the showers placed, next to your Hot water cylinder and feeding into it either somewhere near the top of the cylinder or into the cold feed if so as you have stated then this is a secondary return for the hot water system. or are you saying that you have three pumps in total. 2 on the heating circuit and another for the showers. If you have 2 pumps on the heating circuit how many zone valves do you have? Your house doesnt sound that big.

Thank you Unguided.

To clarify (if I can!) there were three pumps in the old system One for the hot water, the second for the heating system and the third for the shower.

Unfortunately the system was dismantled yesterday as the boiler had packed up. I am told that in the previous system, one pump was for the central heating system and the other for the hot water. I could only switch on the central heating if the hot water came on at the same time. The water from the hot water taps did not gush out when opened. The shower pump is entirely separate - it has its own feed all the way to the house.

I do not believe I had any zone valves, noting my comments above.

Now (in the new system) there will be valve(s) to separate the hot water and central heating. I am told that is the reason we do not need the extra pump. The engineer has said that the pump within the condensing boiler will be sufficient to pump both the heating and hot water systems, including the run of 9 metres (or so) from where it is sited to the beginning of the house. The run (of pipes) within the house would be as for a normal 4 bedroom house.

Is this accurate (that I do not need an extra pump)?

 

[unguided1]

He is right the old system sounds like a bit of a lash up to me

 

[hughs]

He is right the old system sounds like a bit of a lash up to me

Thanks Unguided for your help.

 

[Phoenix Heating]

are u upgrading to a combination boiler?
or are u using a system boiler?

 

[CharterGAS]

the 2 pump system was an old way of doing it and is probably still better than having stupid zone valves!!!

BUt yes you only need he one in the boiler providing the head of the pump is big enough relative to size of system

 

[hughs]

are u upgrading to a combination boiler?
or are u using a system boiler?

Thanks Phoenix.

I am using a system boiler.

the 2 pump system was an old way of doing it and is probably still better than having stupid zone valves!!!

BUt yes you only need he one in the boiler providing the head of the pump is big enough relative to size of system

Thanks CharterGas.

 

[Bagsy]

This system you describe sounds very much like the old SMC sytem (blue pumps), where you had two pumps and also a specified programmer with a relay box. SMC used to be the major supplier of central heating pumps in the 80's. Grundfos came along with a better pump and took over that spot. Eventually SMC as a company went out of business.

The pumps used to be coupled together and there would have been an outlet to the side of one of the pumps, this would have been the hot water circulating outlet.

If this is this system you had, you will require one pump and a set of zone valve/diverter valves to replace the old set up.

Your shower set up will be independent.

I hope this has been helpful.

Regards,

Graham
[DLMURL]http://www.plumbfixit.synthasite.com[/DLMURL]

 

[hughs]

This system you describe sounds very much like the old SMC sytem (blue pumps), where you had two pumps and also a specified programmer with a relay box. SMC used to be the major supplier of central heating pumps in the 80's. Grundfos came along with a better pump and took over that spot. Eventually SMC as a company went out of business.

The pumps used to be coupled together and there would have been an outlet to the side of one of the pumps, this would have been the hot water circulating outlet.

If this is this system you had, you will require one pump and a set of zone valve/diverter valves to replace the old set up.

Your shower set up will be independent.

I hope this has been helpful.

Regards,

Graham
[DLMURL]http://www.plumbfixit.synthasite.com[/DLMURL]

Thanks Graham for your comments. Much appreciated.

 

[plumbnuts]

The additional pump that they have mentioned could be for the secondary return on the hot water system. If the distance from the hot water cylinder to the furtherst hot tap is 15m or more a secondary return is required and this would necessitate an additional bronze pump.
Steve

 

[leakylea]

i had to fit two pumps on a system years ago,i relaced a baxi bermuda with a low content boiler, the boiler was almost directly below where the baxi was in the basement. the cylinder was that far away that the boiler cut out on stat before the cylinder fully got hot, the second pump was set at its minimum setting and i suppose acted as an old circulator would do, an gave the circs to the cylinder a gentle shove