For a shallow-well or jet pump with a 1-inch suction line, the Merrill FVNL100 is a no-lead brass foot valve with a stainless steel spring and strainer, rated 200 psi and 190°F, about 5 inches long and under 2 inches across. For a 1-1/4-inch line, the FVNL125 is the same 710-series valve one size up. Both have female threads and work vertical or horizontal. Match the pipe size the pump calls for; a bigger valve isn’t an upgrade.
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A foot valve combines a check valve and intake screen at the water end of a suction line. Before choosing parts, identify the pump arrangement with our shallow well pump guide. This page does not size a well system or tell you to pull a buried intake yourself.
Foot valve choices compared
| Exact example | Connection or construction | Buying decision |
|---|---|---|
| Merrill FVNL100 | 710 family, 1-inch pipe size | Use only where that connection and the suction design match |
| Merrill FVNL125 | 710 family, 1-1/4-inch pipe size | Different connection and overall dimensions; not an automatic performance upgrade |
| Flomatic 4103E | 60SE family, 1-1/4-inch; dealer option | Confirm the exact body envelope, flow data and current specification |
| Flomatic 5733 | 104P family, 1-1/4-inch; reinforced nylon body; dealer option | Check service compatibility instead of assuming every plastic valve is equivalent |
710 FAMILY · SMALLER OF THE TWO LINKED SIZES
Merrill FVNL100: 1-inch connection
Choose it when the required connection is 1 inch and the exact valve is suitable for the service. Merrill lists FVNL100 in its manufacturer product directory (no longer online). The linked Amazon offer names FVNL100, and its model field matches.
Do not infer the required valve size from the pump outlet alone. Record the suction connection, intake arrangement and pump instructions before ordering. A reducer that makes two threads join does not establish a suitable suction design.
Skip it if the design calls for another size, a different material or a documented performance requirement that you have not checked. The manufacturer’s 710 sheet has inconsistent alloy wording between its heading and materials table. Confirm the required casting specification with the supplier if the alloy matters to your job.
710 FAMILY · LARGER CONNECTION
Merrill FVNL125: 1-1/4-inch connection
Choose it when the suction design specifies 1-1/4 inch and this exact component meets the requirement. Merrill’s 710 specification sheet (merrillmfg.com) identifies FVNL125 as that size and provides an overall dimensional table. Check the complete envelope, not just the thread size, when the intake must pass through a restricted opening.
The sheet permits vertical or horizontal operation for this family. That permission belongs to this documented product; do not apply it to every foot valve. The linked listing names FVNL125 but gives the family name in its model field, so the part named in the title remains an important receiving check.
Skip it if you are adding reducers merely to install a larger-looking valve. Confirm that the pump, suction pipe, valve and fittings have been selected together. Inspect the delivered box and casting identification before the old valve becomes inaccessible.
Flomatic 60SE: dealer alternative
Flomatic’s 60SE page (flomatic.com) lists 4103E as a 1-1/4-inch part with a female threaded connection. The family uses a stainless spring and strainer. Its tables distinguish other sizes and configurations, so “60SE, 1-1/4 inch” alone may not capture every ordering detail.
Choose this dealer option when the project specifies the exact Flomatic part and its current data. Skip it if the intake clearance or hydraulic requirements remain unknown. We did not confirm a qualifying exact new Amazon offer for 4103E, so there is no substitute affiliate button for a similar-looking valve.
Plastic foot valves: check the exact model
Flomatic identifies 104P part 5733 (flomatic.com) as the 1-1/4-inch example in a reinforced nylon family with a polyethylene strainer. That is a specific construction, not a promise that every inexpensive plastic foot valve has the same materials or limits.
Choose this dealer option only when its published service limits and connection suit the system. Skip it where the project specifies another body material or where the fluid is outside the maker’s intended service. Do not use a water-pumping foot valve for fuel, solvents or another liquid merely because the thread fits.
Material labels do not decide the whole purchase. Compare the exact seal, strainer, service conditions, access for replacement and supplier documentation. A part that cannot be identified later can turn a simple service call into a second buying exercise.
Pipe size, screen and intake clearance
Compare the valve’s flow data and screen open area with the actual suction requirement. Flomatic’s installation instructions (flomatic.com) warn against choosing solely by pipe size. The screen intercepts larger debris; it does not turn an unsafe source into drinking water or replace a water-treatment system.
Keep the intake in the arrangement specified by the valve and pump makers, with the required submersion and clearance from sediment. Flomatic calls for vertical installation in its foot-valve instructions. Follow the exact product’s instructions rather than borrowing Merrill’s orientation permission for a Flomatic valve.
Plan how the screen will be reached for service. A screen buried in sediment or packed with debris cannot be corrected by repeatedly restarting the pump. Protect the intake during installation so dirt and thread-sealing material do not enter the valve seat.
Do not improvise a fine suction filter or wrap the strainer in extra mesh without an approved design. Added restriction changes the intake conditions. Ask the pump supplier to evaluate a suitable intake and filtration arrangement if the source carries persistent sand or debris.
Lost prime: diagnose before replacing
Lost prime is a symptom, not a confirmed foot-valve diagnosis. The Pentair shallow-well pump troubleshooting manual (flowandfiltrationsolutions.pentair.com) also identifies air leaks, low water level, blocked intake components and other causes. Stop a pump that is not delivering water and arrange diagnosis; repeated dry running can damage it.
Before authorizing replacement, write down when the problem happens: after sitting, during demand, after service or after a power interruption. Record the pump model and what was changed. Those observations help a well professional decide what to inspect without treating a shopping recommendation as a diagnosis.
A new valve cannot correct every fault elsewhere in the system. Compare pump types in our well pump buying guide if the existing arrangement is uncertain. Do not install extra check valves as a universal cure; follow the pump maker’s required arrangement.
Before ordering or opening the system
- Identify the system. Record the pump model, suction arrangement, pipe connection and actual source conditions.
- Confirm the exact part. Match the complete model and connection. Check the body envelope where access is restricted.
- Check water-service suitability. For potable water, obtain the required exact-model compliance documentation. A coarse screen and a “no lead” product name are not contaminant-removal certifications.
- Plan safe access. Use a qualified well or pump professional for inaccessible intakes, well openings, uncertain lifting arrangements and electrical work.
- Stop and isolate before opening. Shut off power, prevent restart and release pressure using the equipment instructions. Do not loosen a hot or pressurized priming plug.
- Use the pump’s startup procedure. Prime and verify operation as instructed. Never run the pump dry or against a closed discharge, and never leave a failing pump cycling unattended.
Keep the old component until the replacement has been matched and the system operates correctly. Save the new part’s packaging, current specification and service record. If the delivered model differs from the order, resolve that discrepancy before installation.
Foot valve FAQ
What does a foot valve do?
It combines a check valve and intake screen at the water end of a suction pipe. The valve helps retain the water column between pump starts, while the screen intercepts larger debris.
Does losing prime prove the foot valve is bad?
No. Air leaks, low source-water level, blocked intake components and other pump-system problems can produce similar symptoms. Diagnose the system before replacing the valve.
Can a foot valve be installed horizontally?
Only if the exact model’s instructions allow it. Merrill permits horizontal operation for its documented 710 family; Flomatic’s foot-valve instructions call for vertical installation.
Should I buy a larger foot valve for better flow?
Select it with the pump and suction design. A larger thread, extra reducer or material change does not by itself establish better performance.
Does a foot valve filter drinking water?
Its intake screen catches larger debris. It does not establish microbiological safety or replace an appropriately selected and maintained drinking-water treatment system.
How we chose
This document-based guide uses manufacturer model tables, specification sheets and pump instructions. It does not claim hands-on testing. We checked the linked standard new Amazon offers for model identity and in-stock cart availability on October 14, 2026; availability and sellers can change. Unconfirmed alternatives remain dealer options. Read our selection method and about Plumbing Picks.
Primary sources
- Merrill 710 product family (merrillmfg.com): manufacturer identity and screen construction.
- Merrill 710 specification sheet (merrillmfg.com): part sizes, dimensions and permitted orientation; casting wording requires confirmation.
- Flomatic 60SE (flomatic.com): 4103E ordering identity.
- Flomatic 104P (flomatic.com): 5733 ordering identity and nylon construction.
- Flomatic foot-valve installation instructions (flomatic.com): flow selection, screen role and installation orientation.
- Pentair Pro shallow-well jet-pump manual (flowandfiltrationsolutions.pentair.com): startup precautions and differential troubleshooting.